Medical devices, systems, and methods for performing eye exams and eye tracking

ABSTRACT

Apparatus and methods for eye tracking using an optical coherence tomography (OCT) device are disclosed. Such eye tracking may be performed by using information about the shape of the cornea and the corneal apex or using the iris/pupil border obtained using the OCT device.

PRIORITY INFORMATION AND INCORPORATION BY REFERENCE

The present application claims the priority benefit of U.S. ProvisionalApplication No. 62/330,059, filed Apr. 30, 2016, and U.S. ProvisionalApplication No. 62/333,112, filed May 6, 2016, the entirety of both ofwhich are hereby incorporated by reference herein. Any and allapplications for which a foreign or domestic priority claim isidentified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference.

BACKGROUND Field

Embodiments of the present disclosure relate to the field of healthcare,including for example, devices, systems, methods of automating theprovision of diagnostic healthcare services to a patient as part of anexamination meant to detect disorders or diseases. In some but not allinstances, these healthcare services may apply only to eye careencounters, exams, services and eye diseases.

Description of the Related Art

Many people visiting medical offices often use the same equipment.Cross-contamination has become a problem of increasing concern,especially during certain periods such as flu season. As the provisionof healthcare becomes more automated, fewer office personnel may bepresent to clean devices between uses. Accordingly systems and methodsfor improving hygiene are desirable.

SUMMARY

A wide range of embodiments are described herein. In some embodiments, amask may comprise a distal sheet member having one or more substantiallyoptically transparent sections and a proximal inflatable member having arear concaved surface that may face a first patient's face when in use.The rear concaved surface may be configured to conform to contours ofthe first patient's face. The inflatable member may have two cavitiestherein. The two cavities may be generally aligned with the one or moresubstantially optically transparent sections, and may extend from therear concaved surface toward the distal sheet member such that thecavities define two openings on the rear concave surface. The rearconcave surface may be configured to seal against the first patient'sface such that the first patient's eyes align with the two cavities, sothat the rear concave surface forms seals around a peripheral region ofthe first patient's eye sockets that inhibit flow of fluid into and outof the cavities. The mask may further comprise an ocular port providingaccess to at least one of the two ocular cavities for fluid flow intoand out of the at least one of the two ocular cavities and an inflationport providing access to inflate the inflatable member.

In various embodiments, the rear concaved surface may be configured toconform to the contours of the first patient's face with inflation ofthe inflatable member via the inflation port. The inflatable member maybe underinflated and the rear concaved surface may be configured toconform to the contours of the first patient's face with inflation ofthe underinflated inflatable member via the inflation port. The rearconcaved surface may be configured to conform to the contours of thefirst patient's face with application of negative pressure to theinflatable member via the inflation port. The mask may further compriseparticulate matter disposed within the inflatable member. Theparticulate matter may be configured to pack together with applicationof a negative pressure to the inflatable member via the inflation port,so that the rear concaved surface conforms to the contours of the firstpatient's face.

In various embodiments, the rear concaved surface may be configured toconform to contours of a second patient's face, wherein a contour of thesecond patient's face is different from a contour of the first patient'sface. The seals may be air-tight. The mask may further comprise a lipextending into at least one of the two cavities from a perimeter of atleast one of the two openings, the lip having distal ends curving towardthe distal sheet member in a default position, the distal endsconfigured to move rearwardly such that the lip seals against the user'sface upon introduction of positive pressure into the at least one of thetwo cavities. The inflatable member may be opaque.

In various embodiments, the distal sheet may be configured to interfacewith a medical device, which may be an eye exam device. The mask may beconfigured to couple with a docking portion on a medical device. Themask may be configured to couple with the docking portion via a flangethat slides into a slot of the docking portion. The inflation port andthe ocular port of the mask may be configured to couple with conduitends on a medical device. The ocular port and the inflation port mayinclude a male portion, wherein the conduit ends on the medical deviceinclude a female portion configured to slidably receive the maleportion. The ocular port and the inflation port may be configured tocouple with the conduit ends on the medical device substantiallysimultaneously.

As described herein, an ophthalmic diagnostic instrument such as anoptical coherence tomography device that may or may not employ ahygienic barrier, e.g., mask, such as described above may be used toassess the condition of a persons eyes. This diagnostic system mayobtain images of the structures of the eye using imaging technology suchas optical coherence tomography and also a scanning laserophthalmoscope. To assist with such imaging and/or provide additionaldiagnostics, the ophthalmic diagnostic instrument may additionallyinclude a system for tracking the position and/or orientation (e.g.,gaze direction) of the subject's eyes whose eyes and vision are beingevaluated.

In one embodiment, a method of detecting an eye gaze direction isdescribed. The method may include performing a first OCT scan of thefront or anterior segment of the eye, determining a location of acorneal apex of the eye based on detecting the outer surface of thecornea in the OCT scan, and calculating an eye gaze direction based atleast in part on the location of the corneal apex. The first OCT scanmay include at least three longitudinal A-scans spaced linearly along alateral direction. Determining a location of a corneal apex may includedetermining a longitudinal coordinate of the outer surface of the corneafor at least three of the longitudinal A-scans and fitting atwo-dimensional parabolic function to the determined longitudinalcoordinates. In another embodiment, determining a location of a cornealapex may include determining a longitudinal coordinate of the outersurface of the cornea for at least four of the longitudinal A-scans andfitting a two-dimensional parabolic function to the determinedlongitudinal coordinates. Determining a location of a corneal apex mayfurther include calculating the location of the apex of thetwo-dimensional parabolic function. Determining an eye gaze directionmay include calculating an axis of symmetry for a two-dimensionalparabolic function or calculating a normal vector to a corneal apexlocation in a two-dimensional parabolic function.

The method may further include performing a second OCT scan of the frontor anterior segment of the eye wherein the second OCT scan is not in thesame plane as the first OCT scan. In some embodiments, the plane of thesecond OCT scan may be substantially perpendicular to the plane of thefirst OCT scan. In other embodiments, the plane of the second OCT scanis offset by 30°, 45°, 60°, or other angles between 0° and 90° from theplane of the first OCT scan. The location of the corneal apex may bedetermined based on the first and the second OCT scans. In oneembodiment, the first and second OCT scans each include at least threelongitudinal A-scans. Determining a location of a conical apex in eachof the first and second OCT scans may include determining a longitudinalcoordinate of the outer surface of the cornea for at least three of thelongitudinal A-scans in each OCT scan and fitting a two-dimensionalparabolic function to the determined longitudinal coordinates in eachOCT scan. The combination of the corneal apex locations derived fromthese two parabolic functions can be used to determine a gaze direction.In another embodiment, the first and second OCT scans each include atleast four longitudinal A-scans. Determining a location of a cornealapex in each of the first and second OCT scans may include determining alongitudinal coordinate of the outer surface of the cornea for at leastfour of the longitudinal A-scans in each OCT scan and fitting atwo-dimensional parabolic function to the determined longitudinalcoordinates in each OCT scan. A parabolic function derived from fourpoints has advantages over a parabolic function derived from threepoints since the four-point derivation defines the tilt of the parabolicfunction. A gaze direction can be determined in each of the first andsecond OCT scans by calculating the gaze vector that passes through andis normal to the corneal apex location. The slope of this vector is thesame as the calculated tilt of the parabolic function in eachtwo-dimensional OCT scan. It will be apparent to one skilled inmathematics that the final, single three-dimensional gaze vector can bedetermined by combining these two-dimensional vectors, taking intoaccount the angle separating the planes containing these two OCT scansand gaze vectors when combining the vectors. In another embodiment,determining a location of a corneal apex may include calculating athree-dimensional paraboloid function based on the fittedtwo-dimensional parabolic functions of the first OCT scan and the secondOCT scan, and calculating the location of the apex and normal gazevector of the three-dimensional paraboloid function. Since there may beerrors in detecting the corneal surface from OCT images, the accuracy ofthis measurement may be enhanced by using multiple iterations ofcalculations based on different samples of longitudinal components fromthe OCT scans to find the most commonly represented, median, or meangaze vector and corneal apex positions.

The first and second OCT scans may include a total of at least sixlaterally spaced longitudinal A-scans. Determining a location of aconical apex and the eye gaze direction may include determining alongitudinal coordinate of the outer surface of the cornea for at leastsix of the longitudinal A-scans, fitting a three-dimensional paraboloidfunction to the determined longitudinal coordinates, and calculating thelocation of the apex and direction of the gaze vector of thethree-dimensional paraboloid function.

In another embodiment, a method of detecting an eye gaze directioncomprises using the pupil/iris boundary. The method may includeperforming an OCT scan of at least a portion of an iris and at least aportion of a pupil of an eye, determining a location of a pupillaryborder of the eye based on the OCT scan, and calculating an eye gazedirection based at least in part on the location of the pupillaryborder. The method may further include determining a lateral distancebetween the pupillary border and a longitudinal meridian. In oneembodiment, the location of the pupillary border may be determined inone dimension. In other embodiments, the location of the pupillaryborder may be determined in two dimensions, such as x and y orhorizontal and vertical, to locate a point that is closest to thelongitudinal meridian. In other embodiments, more than one pupillaryborder, such as obtained from left and right of a longitudinal meridian,may be determined in a single OCT scan. Information from these more thanone measurement of the location of pupillary borders may be combined,such as by averaging or fitting them to a function, to determine arelationship to a longitudinal meridian. In still other embodiments,more than one pupillary border may be determined in more than one OCTscan. Information from these more than one measurement of the locationof pupillary borders may be combined, such as by averaging or fitting toa function such as a circle, to determine a relationship to alongitudinal meridian. The eye gaze location may be calculated based onthe lateral distance between a pupillary border and a longitudinalmeridian. The eye gaze location may also be calculated based on adistance between a function derived from one or more pupillary borderpoints and a longitudinal meridian.

The OCT scan may include a first two-dimensional B-scan taken along afirst lateral direction. The OCT scan may further include a secondtwo-dimensional B-scan taken along a second lateral direction differentfrom the first lateral direction. The location of the pupillary bordermay be determined in two directions and mathematically fitted to afunction such as a circle or plane. Since three points can be used todefinitively describe a circle or plane, various three pointcombinations of the four pupillary border points may be usedindependently to derive the function to fit each set of three points.The consensus function that best fits all of these functions, such as byminimizing maximum error, can then be determined. In some embodiments,the consensus function is derived using Random Sample Consensus(RANSAC). In some embodiments, noise or outlier rejection algorithms maybe used to eliminate one of the four points to enable calculation of afunction from the remaining three points. Calculating an eye gazedirection may include calculating an angle between a point of gaze and alongitudinal axis, calculating a difference in pupillary diameter todetermine foreshortening, and thus tilt, of the circle delineating thepupil, calculating a normal to a fitted function such as a plane orcircle, or combining normal vectors from two lines connecting thepupillary border points in each of the first and second B-scans. Theorigin (or suitable location) of the gaze vector, which often coincideswith the center of the pupil, can be determined as a combination of themidpoints between the measured locations of the pupillary borders ineach of the OCT scans or as the center of the function derived from thepupillary border points.

In another embodiment, a method of tracking the gaze direction of an eyeis described. The method may include determining a first gaze directionof the eye at a first time based on one or more OCT scans of the eye,determining a second gaze direction of the eye at a second time based onone or more OCT scans of the eye, and calculating a change in gazedirection of the eye based on the first gaze direction and the secondgaze direction. Calculating a change in gaze direction of the eye mayinclude calculating a lateral displacement of a structure of the eyebetween the first time and the second time. The first gaze direction maybe determined based on a first location of a corneal apex of the eye,and the second gaze direction may be determined based on a secondlocation of the corneal apex of the eye. The first gaze direction may bedetermined based on a gaze vector calculated from the first OCT scan ofthe eye and the second gaze direction may be determined based on asecond gaze vector calculated from the second OCT scan of the eye. Thefirst gaze direction may be determined based on a first location of apupillary border of the eye, and the second gaze direction may bedetermined based on a second location of the pupillary border of theeye.

Some embodiments relate to the utilization of devices that replace,augment or enhance human laborers in a clinical health care setting.These devices may be used alone or in conjunction with other devicesused in exams such as exams of the eye.

For purposes of this summary, certain aspects, advantages, and novelfeatures of the invention are described herein. It is to be understoodthat not necessarily all such aspects, advantages, and features may beemployed and/or achieved in accordance with any particular embodiment ofthe invention. Thus, for example, those skilled in the art willrecognize that the invention may be embodied or carried out in a mannerthat achieves one advantage or group of advantages as taught hereinwithout necessarily achieving other advantages as may be taught orsuggested herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features, aspects and advantages of the presentinvention are described in detail below with reference to the drawingsof various embodiments, which are intended to illustrate and not tolimit the invention. The drawings comprise the following figures inwhich:

FIG. 1 schematically illustrates a perspective view of one embodiment ofa mask which is inflatable and includes a framework that forms twocavities for the oculars.

FIGS. 2 a-2 b schematically illustrates a mask removably attached to amedical device.

FIG. 3 schematically illustrates a user wearing a mask that provides,for example, an interface to a medical device such as a diagnosticdevice that is used by many patients.

FIG. 4 schematically illustrates a perspective view of anotherembodiment of a mask with an inflatable framework that is partitionedinto two separately inflatable sections.

FIG. 5 schematically illustrates a cross section of the mask in FIG. 4taken along the lines 5-5.

FIG. 6 schematically illustrates a perspective view of anotherembodiment of a mask with a seal around the ocular cavities.

FIG. 7 a schematically illustrates a side view of one embodiment of amask displaced a first distance from a medical device.

FIG. 7 b schematically illustrates a side view of another embodiment ofa mask displaced a second distance from the medical device.

FIG. 8 schematically illustrates a schematic diagram of a system forcontrolling, monitoring, and providing fluid to a mask.

FIG. 9 schematically illustrates a schematic diagram an electronic examportal.

FIG. 10 schematically illustrates a healthcare office map.

FIG. 11 schematically illustrates a block diagram of a sample healthcareencounter.

FIG. 12 schematically illustrates a binocular eye examination systembased on optical coherence tomography.

FIG. 13 schematically illustrates a display of eye examination data.

FIGS. 14A-14D schematically illustrate a mask having opticallytransparent sections that are tilted or sloped upward or downward andinclude an anti-reflection (AR) coating to reduce retro-reflection oflight from an incident probe beam from an optical coherence tomographyinstrument back into the instrument.

FIGS. 15A and 15B schematically illustrate the effect of a tilted orsloped window on a probe beam from the OCT instrument which reducesretro-reflection into the optical coherence tomography instrument.

FIGS. 15C-15E schematically illustrate the effect of a tilted or slopedwindow on a mask on the light reflected from an incident OCT probe beamand how tilting or sloping the window beyond the angle of the steepestray of light from the probe beam can reduce retro-reflection into theoptical coherence tomography instrument.

FIGS. 16A-16D schematically illustrate a mask having opticallytransparent sections that are tilted or sloped nasally or temporally toreduce retro-reflection of light from an incident probe beam back intothe optical coherence tomography instrument.

FIGS. 17A-17E schematically illustrate a curved window on a mask anddemonstrates how the location of the window with respect to the focus ofthe OCT instrument (e.g., oculars or eyepieces) can vary the amount ofretro-reflection of light from the optical coherence tomographyinstrument back into the OCT instrument.

FIGS. 18A-18D schematically illustrate a mask having opticallytransparent sections that are curved to reduce retro-reflection of lightfrom the optical coherence tomography instrument back into the OCTinstrument.

FIG. 19 schematically illustrate a curved window on a mask disposedforward of a pair of eyes separated by an interpupilary distance whereinthe window is increasing sloped more temporal from a center line throughthe window thereby exhibiting wrap that reduces retro-reflection oflight from the optical coherence tomography instrument back into the OCTinstrument.

FIGS. 20A-20D schematically illustrate a mask having an optical windowhaving wrap as well as curvature in the superior-inferior meridian toreduce retro-reflection of light from the optical coherence tomographyinstrument back into the OCT instrument.

FIGS. 21A-21D, 22, 23, 24, 25A-25D, 26, and 27 schematically illustratedifferently shaped mask windows.

FIGS. 28A-28D schematically illustrate design considerations indetermining the slope of the window at different distances from thecenterline through the mask.

FIGS. 29 a-29 c illustrate example methods of scanning an eye usingoptical coherence tomography (OCT) to determine gaze direction.

FIG. 30 a is a cross sectional view of an eye taken at a horizontalplane depicting an eye looking straight ahead.

FIG. 30 b is a cross sectional view of an eye taken at a horizontalplane depicting an eye looking to the left.

FIG. 30 c is a cross sectional view of an eye taken at a horizontalplane depicting an eye looking to the right.

FIG. 30 d depicts a front view of a pupil of the forward-looking eyedepicted in FIG. 30 a.

FIG. 30 e depicts a front view of a pupil of the left-looking eyedepicted in FIG. 30 b.

FIG. 30 f depicts a front view of a pupil of the right-looking eyedepicted in FIG. 30 c.

FIG. 31 a depicts a horizontal two-dimensional OCT B-scan of theforward-looking eye depicted in FIG. 30 a.

FIG. 31 b depicts a horizontal two-dimensional OCT B-scan of theleft-looking eye depicted in FIG. 30 b.

FIG. 31 c depicts a horizontal two-dimensional OCT B-scan of theright-looking eye depicted in FIG. 30 c.

FIG. 31 d depicts a vertical two-dimensional OCT B-scan of theforward-looking eye depicted in FIGS. 30 a and 31 a.

FIG. 31 e depicts a vertical two-dimensional OCT B-scan of theleft-looking eye depicted in FIGS. 30 b and 31 b.

FIG. 31 f depicts a vertical two-dimensional OCT B-scan of theright-looking eye depicted in FIGS. 30 c and 31 c.

FIGS. 32 a-32 c illustrate an example method of determining an eye gazeangle based on lateral movement of a pupillary border.

FIGS. 32 d-32 i illustrate an example method of detecting pupillaryborder points using OCT B-scans.

FIGS. 32 j-32 m illustrate an example method of detecting a pupillaryborder shape using OCT B-scans.

FIGS. 32 n-32 o are cross-sectional views illustrating the movement of acorneal apex relative to a longitudinal meridian.

FIGS. 32 p-32 s illustrate an example method of detecting an eye gazedirection vector from a detected pupillary midpoint based on two OCTB-scans.

FIGS. 32 t-32 w illustrate an example method of detecting an eye gazedirection vector based on two OCT B-scans.

FIGS. 33 a-33 c illustrate an example method of determining an eye gazeangle based on lateral movement of a corneal apex.

FIGS. 34 a-34 d illustrate an example method of calculating a paraboloidfunction representing the shape of a cornea based on multipletwo-dimensional OCT scans.

FIG. 35 illustrates an example method of directly calculating aparaboloid function representing the shape of a cornea.

DETAILED DESCRIPTION

Some embodiments disclosed herein provide an instrument for imaging theeye and performing ophthalmic diagnostic tests. Such an instrument maycomprise, for example, optical coherence tomography (“OCT”) devices.Some embodiments disclosed herein provide apparatus and methods for eyetracking using, for example, an OCT device. Some embodiments disclosedherein provide an inflatable mask that can interface with medicaldevices, such as medical diagnostic devices, such as optical coherencetomography (OCT) devices. The inflatable mask can serve a variety ofpurposes, including maintaining a barrier between the patient and themedical device to ensure cleanliness and hygiene, providing comfort tothe patient, and stabilizing the patient's location with respect to themachine. In some embodiments, the inflatable mask can form air-tightocular cavities around the patient's eyes, allowing for pressurizationof the ocular cavities, in order to obtain ocular measurements.Additionally, various embodiments of an automatic portal system and anautomated eye examination are disclosed herein.

Embodiments of the invention will now be described with reference to theaccompanying figures, wherein like numerals refer to like elementsthroughout. The terminology used in the description presented herein isnot intended to be interpreted in any limited or restrictive manner,simply because it is being utilized in conjunction with a detaileddescription of certain specific embodiments of the invention.Furthermore, embodiments of the invention may comprise several novelfeatures, no single one of which is solely responsible for its desirableattributes or which is essential to practicing the embodiments of theinventions herein described.

To assist in the description of various components of the eye trackingmethods and systems, the following coordinate terms are used. A“longitudinal axis” is generally parallel to the optical axis, or axisof symmetry, of an eye when the eye is looking straight ahead. Thelongitudinal axis extends from the posterior to the anterior or anteriorto posterior. A “lateral axis” is normal to the longitudinal axis. Forexample, FIG. 29 a depicts a view of an eye viewed from along alongitudinal axis, as well as lines parallel to a horizontal lateralaxis and a vertical lateral axis representing OCT scanning paths.

In addition, as used herein, “the longitudinal direction” refers to adirection substantially parallel to the longitudinal axis, “thehorizontal lateral direction” refers to a direction substantiallyparallel to the horizontal lateral axis, and “the vertical lateraldirection” refers to a direction substantially parallel to the verticallateral axis. Throughout the application, x, y, and z directions and/oraxes may be used to indicate direction. Description of a z directionrefers to a longitudinal direction, while x and y directions refer tolateral directions, such as horizontal lateral and vertical lateraldirections. For example, FIG. 29 a depicts an eye viewed in thelongitudinal (z) direction with a line in the horizontal lateral (x)direction and a line in the vertical lateral (y) direction normal toboth the horizontal lateral line and the longitudinal direction of view.As used herein, a “longitudinal coordinate” refers to a coordinate alonga longitudinal axis, such as a z coordinate. For example, in the contextof a 1-dimensional OCT A-scan taken at a fixed lateral location, a“longitudinal coordinate” of a structure lies along a longitudinal linein a longitudinal direction, and may be equivalent to a height, depth,distance, or z location of the structure along a longitudinal directionof the OCT A-scan.

Inflatable Medical Interface

Referring to FIG. 1 , in one embodiment, a mask 100 includes a distalsheet member (distal portion) 118 which has optically transparentsections 124, and a proximal inflatable member (proximal portion) 154having a generally concaved rear surface 122. In use, the rear concavedsurface 122 faces the patient's face and conforms to the patient's face,according to some embodiments. As used herein the terms “user” or“patient” or “subject” or “wearer” may be used interchangeably. StillReferring to FIG. 1 , the inflatable member 154 can have two cavities160 a, 160 b which are aligned with the optically transparent sections124. In some embodiments, the cavities 160 a, 160 b extend from a distalsheet 118 to the rear concave surface 122 and define two openings 162 onthe rear concave surface 122. In use, the patient's eyes align with thetwo cavities 160 a, 160 b, so that the rear concave surface 122 formsseals around the patient's eye sockets or face, e.g. forehead andcheeks, inhibiting flow of fluid into and out of the cavities 160 a, 160b. In addition, the mask 100 can include ports 170 a-b, 180 a-b whichprovide access to control flow of fluid (e.g. air) into and out of thecavities 160 a, 160 b.

In some embodiments, the mask 100 can interface with a medical device.With reference to FIGS. 2 a-2 b , there is illustrated one embodimentwhereby the mask 100 is placed on a separate device 112. In someembodiments, the separate device 112 is a medical device, such as adiagnostic or therapeutic device. In some embodiments, the separatedevice 112 is an ophthalmic device, such as a device for the eye, andmay be an optical coherence tomography device (“OCT”) that may contain ahousing and instrumentation contained therein. The mask 100 may be usedwith a wide range of medical devices 112, such as for example an OCTdevice such as disclosed herein, as well as other OCT devices and othermedical devices 112. In some embodiments, the medical device 112 canreceive and removably connect to the mask 100. The mask 100 can beconfigured to connect to the medical device 112, adhere to one or moresurfaces of the medical device 112, or be mechanically fixed to themedical device 112, or be secured to the medical device 112 in any otherway (e.g. clamps, straps, pins, screws, hinges, elastic bands, buttons,etc.), such that the mask 100 is removable from the medical device 112without damaging the mask 100.

In one embodiment, a docking portion 114, which may include an opticalinterface such as for example a plate, can be included on the medicaldevice 112. The docking portion 114 can also include a slot 116 forreceiving a mask 100. In some embodiments, the mask 100 includes aflange 164 that extends laterally outward past a side of the inflatablemember 154 on the distal sheet 118 for slideably engaging with the slot116. The mask 100 can be inserted into the slot 116 and slide down to afinal locking position 120. In another embodiment, the flange 164 can beon the medical device 112 and the slot 116 can be on the mask 100.

With reference to FIG. 3 , there is illustrated an example of a mask 100worn by a user over the user's eyes. In various embodiments, the mask100 may be removably attached to the wearer with an adhesive, an elasticband, a Velcro band, a strap, a buckle, a clip, and/or any othersuitable fastener or mechanism. In some embodiments, the mask 100 caninclude mechanisms for both attaching to the wearer and attaching to themedical device 112. In other embodiments, a patient may use the mask 100without any straps, bands, etc. that attach to the user. For example,referring to FIGS. 2 a-b , the patient may simply move his/her face inalignment and in contact with the mask 100, which is secured to themedical device 112. In another embodiment, a patient who has a mask 100secured to his/her face may position himself/herself properly withrespect to the medical device 112, so that the distal sheet 118interfaces with the medical device, 112, and the medical device 112 cantake readings.

Returning to FIG. 1 , one embodiment of the mask 100 comprises aninflatable framework 154 having an inflatable chamber 154 a, twocavities 160 a, 160 b, a frontward surface formed by a distal sheetmember 118, and a rearward surface 122. It will be understood that“inflatable,” as used herein, can include “deflatable,” and vice versa.Thus, in some embodiments, an “inflatable” framework 154 or chamber 154a can be deflatable, and a “deflatable” framework 154 or chamber 154 acan be inflatable. Referring to FIG. 1 , cavities 160 a, 160 b mayextend between the distal sheet member 118 and the rearward surface 122.In some embodiments, the frontward member 118 includes a window member124, which can be substantially optically transparent in someembodiments, with minimal to no effects on the optics of a medicaldevice 112 (e.g. an OCT device) which can interface with the mask 100,although some embodiments may introduce optical effects. In someembodiments, the distal sheet member 118 can be rigid. In someembodiments, the distal sheet member 118 can be made of polycarbonate,poly(methyl methacrylate), or glass. Other materials can be used. Inother embodiments, the distal sheet member 118 can be flexible. Thedistal sheet member 118 can have a thickness of less than 0.1 mm, 0.1mm, 0.5 mm, 1 mm, 2 mm, 4 mm, or more. In one embodiment, the windowmember 124 may be adjacent to the inflatable framework 154. Thus, thewindow member 124 may form a frontward surface of a cavity 160 a, 160 b.Further, the window member 124 may be aligned with the cavities 160 a,160 b. In addition, the cavities 160 a, 160 b can define openings on therearward surface, defined by perimeters 162. Referring to FIG. 4 , theinflatable framework 154 can have two separately inflatable chambers 150a, 150 b. Still referring to FIG. 4 , in one embodiment, one inflatablechamber 150 a can have a cavity 160 a therein, and another inflatablechamber 150 b can have another cavity 160 b therein.

The distal sheet member 118 may be substantially flat and the rearwardsurface 122 may be generally curved and concave according to oneembodiment. Referring to FIG. 4 , in one embodiment the thickness of themask 100 is thinnest at the center 156 and thickest toward the outeredges 158, with the thickness decreasing from the outer edges 158 towardthe center 156, thereby defining a curved and concave rearward surface122.

During use, a patient's face is brought in contact with the rearwardsurface 122 of the mask, such that the patient's eyes are aligned withthe cavities 160 a, 160 b, and the patient “sees” into the cavities 160a, 160 b. Thus in some embodiments, the cavities 160 a, 160 b may bereferred to as ocular cavities 160 a, 160 b. In one embodiment, only theportion of the distal sheet member 118 that aligns with the patient'seyes may be optically transparent, with other portions opaque ornon-transparent.

In some embodiments, the rear concaved surface 122 of the mask 100 canseal against a patient's face around the general area surrounding thepatient's eyes sockets, thereby forming a seal around the patient's eyesockets. The seal may be air-tight and liquid-tight according to someembodiments. In some embodiments, a seal may be formed between the userand the mask 100 without the need for assistance from additionalpersonnel. In some embodiments, various portions of the patient's facecan form the seal around the ocular cavities 160 a, 160 b. For example,the patient's forehead, cheekbones, and/or nasal bridge (e.g. frontalbone, supraorbital foramen, zygomatic bone, maxilla, nasal bone) canform a seal around the ocular cavities 160 a, 160 b. As used herein,reference to a “peripheral region” around the eye socket shall refer toany combination of the above.

FIG. 5 illustrates a top view of a patient wearing a mask 100. The mask100 in FIG. 5 is a cross-section of the mask 100 taken along line 5-5 inFIG. 4 . Referring to FIG. 5 , as seen from the view of the patient, themask 100 comprises a right cavity 160 b, such as a right ocular rightcavity, a left cavity 160 a, such as a left ocular cavity, a rightinflatable chamber 150 b, and a left inflatable chamber 150 b. The walls172 of the ocular cavities 160 a, 160 b, the window members 124, and thehead of the user 195 may form an air-tight enclosed area. The head ofthe user 195 (e.g. the peripheral region around the user's eye sockets)forms a seal with the rearward perimeters 162 of the cavities 160 a, 160b, thus allowing the cavities 160 a, 160 b to hold air or fluid. Thisseal may be capable of holding air or fluid pressures of, for example,0.5 psi, 1 psi, or 5 psi or pressures therebetween. Higher or lowerpressures are also possible.

Still referring to FIG. 5 , some embodiments include inlet assemblies155 a, 155 b. The inlet assemblies may include ports 170 a-b, 180 a-b,allowing access to the inflatable chambers 150 a, 150 b, and/or thecavities 160 a, 160 b.

Air, fluid, and/or other substances can be introduced into the ocularcavities 160 a, 160 b, via ports 180 a, 180 b, 185 a, 185 b. Air may beintroduced into the left ocular cavity 160 a by supplying an air source(e.g. via a pump) to the port at 180 a. Thus, following the path of theair, the air may enter the port at 180 a, then exit the port at 185 aand into the leftocular cavity 160 a (180 a and 185 b represent two endsof the same path). Similarly, regarding the right ocular cavity 160 b,air may enter the port at 180 b, then exit the port at 185 b and intothe right ocular cavity 160 b.

Accordingly, in some embodiments, pressure inside the ocular cavities160 a, 160 b may be controlled by adjusting the amount of air into andout of the ports 180 a, 180 b. Further, the air tight seal formedbetween the patient's face and the mask 100 can prevent unwanted leaksinto or out of the ocular cavities 160 a, 160 b. This can beadvantageous when air or fluid is used to challenge or test a bodyfunction. For example, air pumped into sealed air chamber cavities 160a, 160 b in front of the eye can create positive pressure which can beused to press on the eye for the purposes of measuring the force ofglobe retropulsion or measuring intraocular pressure. In addition, aircan be directed to the cornea, which is imaged with OCT. In someembodiments, air is pumped into the ocular cavities 160 a, 160 b toachieve a pressure of up to 1-2 psi. In some embodiments, the airsupplied to the ocular cavities 160 a, 160 b is supplied by ambientsurroundings, such as the ambient air in a clinical room using forexample a pump.

In some embodiments, chamber ports 170 a, 170 b, 175 a, 175 b provideaccess to inflatable chambers 150 a, 150 b for inflating or deflatingthe chambers 150 a, 150 b. The chambers 150 a, 150 b may be inflated byintroducing an air source (e.g. via a pump) to the ports at 170 a, 180a. Thus, for example, following the path of the air, the air may enterthe port at 170 a, then exit the port at 175 a and into the leftinflatable chamber 150 a, thereby inflating that chamber 150 a. Theright chamber 150 b may be inflated in a similar manner. Negativepressure (e.g. a vacuum) can be applied to the ports 170 a, 170 bconnected to the inflatable chambers 150 a, 150 b, thereby deflating thechambers 150 a, 150 b. As used herein, “deflating” shall includeapplying negative pressure.

In some embodiments, inflating the chambers 150 a, 150 b can cause themask 100 to conform to the contours of a user's face. In addition,deflating the chambers 150 a, 150 b can cause the mask 100 to conform tothe contours of a user's face. Further, inflating or deflating thechambers 150 a, 150 b can adjust a thickness of the mask 100, thuschanging the distance between a user (who may face the rear concavedsurface 122) and a medical device 112 (which may be interfaced with thedistal sheet member 118).

In various embodiments, a port 170 a-b, 180 a-b is provided for eachchamber 150 a, 150 b and cavity 160 a, 160 b. For example, referring toFIG. 5 , there is illustrated a port 185 b for the right cavity, a port175 b for the right inflatable chamber 150 b, a port 185 a for the leftcavity 160 a, and a port 175 a for the left inflatable chamber 150 a.

In one embodiment, two ports may be provided for one inflatableframework 154. For example, returning to FIG. 1 , one port 170 b isprovided on the right side of the inflatable framework 154, and anotherport 170 a is provided on the left side of the inflatable framework 154.Providing two ports for one chamber 154 can help to equalize thedistribution of substances (e.g. air or fluid) in the chamber 154 byallowing access to the chamber 154 at different regions. In oneembodiment, the inflatable framework 154 does not include any ports. Forexample, the inflatable framework 154 may be pre-formed as desired, byfilling it with a desired volume of fluid or air. Ports 170 a-b, 180 a-bmay be added, removed, arranged, or configured in any suitable manner.

In some embodiments, the mask 100 advantageously can conform to apatient's face, thereby allowing the formation of a complete air-tightseal between the peripheral region around a user's eye sockets and therear concaved surface 122 around the ocular cavities 160 a, 160 b.Accordingly, the rearward perimeter 162 of the cavities 160 a, 160 b canbe configured to sealingly engage a periphery of a patient's eye socket.In some embodiments, the mask 100 includes a recess 168 (see e.g. FIGS.1, 4, 6 ), allowing room for a patient's nose, so that the mask 100forms a seal against the parts of a patient's face with a lower degreeof curvature, increasing the surface area of the patient's face to whichthe mask 100 conforms.

In one embodiment, the air-tight seal can be formed by inflating theinflatable framework 154. In some embodiments, the inflatable framework154 can resemble a bag. In some embodiments, a mask 100 with arelatively deflated framework 154 is provided to a patient. Because thebag 154 is deflated, it may exhibit some “slack.” The patient's face maybe brought in contact with the mask 100, and then the bag 154 may beinflated, causing the bag 154 to inflate around the contours of thepatient's face and thereby conform to the patient's face. Accordingly, acomplete air-tight seal can be formed between the patient's face and therear concaved surface 122 around the ocular cavities 160 a, 160 b. Thebag 154 may be inflated by introducing air, gas, fluid, gel, or anyother suitable substance. In addition, the bag 154 can be deflated,causing the mask 100 to disengage from the patient's face, according toone embodiment.

In one embodiment, an air-tight seal is formed by applying a vacuum tothe inflatable framework 154. In some embodiments, when the framework154 is filled with particulate matter, such as coffee grounds, aplasmoid transformation to a semi-solid but form-fitting filler can beachieved by subjecting the particulate matter to a vacuum. For example,the framework 154 can be molded into shape easily when particulatematter is loosely contained in the framework 154, similar to a bean bag.A patient's face may then be brought into contact with the mask 100.Applying a vacuum to the bag 154 causes the particulate matter to packtightly, thereby causing the bag 154 to conform to the contours of apatient's face. The tightly packed particulate matter can thus undergo aplasmoid transformation to a solid, while still allowing the framework154 to conform to the patient's face and create an air-tight seal.

To facilitate the seal between a patient and the cavities 160 a, 160 b,the mask 100 can be configured with a lip 194 around the perimeter 162of a cavity 160 a, 160 b, as illustrated in FIG. 6 . FIG. 6 illustratesa lip 194 with a cut-away portion 161 showing the curvature of the lip194. In one embodiment, the lip 194 comprises a first end 196 attachedto the perimeter 162 of the cavity 160 a, 160 b and a second end 198extending partially into the cavity 160 a, 160 b. In one embodiment, theedge 198 of the lip 194 may extend more or less and curl inward, asillustrated in FIG. 6 . In one embodiment, the first end 196 and secondend 198 define a curve, such that the lip 194 curls inwardly partiallyinto the cavity 160 a, 160 b. Further, the lip 194 can be flexible andconfigured to extend in a rearward direction (e.g. toward the rearwardsurface 122). Thus, when pressure is introduced inside the cavity 160 a,160 b, and pressure exerts a force in a rearward direction, the lip 194can move rearwardly. When the inflatable framework 154 is sealed with aperipheral region around a user's eye socket, and the lip 194 movesrearwardly, the lip 194 can seal against the user's eye socket,preventing pressure from escaping.

In some embodiments, the mask 100 can be configured to be comfortable byfilling the chambers 160 a, 160 b with soft gel fillers, particulatefillers such as foam beads or sand, or air fillers.

In one embodiment, the mask 100 can be custom made to fit the specificpatient using it. For example, the mask 100 may be molded for a specificpatient in a clinic. Thus, the mask 100 can be uniquely customized for aparticular patient according to one embodiment. In another embodiment,the mask 100 is a “one size fits all” mask 100. Other embodiments arepossible, including differential sizing based on age, height or facialstructure. In some embodiments, the mask 100 is pre-inflated. Inaddition, air-tight seals can be formed between the rear curved surface122 of the mask around the ocular cavities 160 a, 160 b and theperipheral region around a patient's eye sockets (e.g. via a lip) whenthe mask 100 is pre-inflated.

FIGS. 7 a-7 b illustrate side views of a user with a mask 100 beingexamined or treated by a medical device 112 according to one embodiment.

It will be appreciated that the FIGS. 7 a-7 b are schematic drawings andmay possibly exaggerate the variation in size for illustrative purposes.The medical device 112 shown in FIGS. 7 a-7 b can be an OCT device.Inflating the mask 100 can increase the thickness of the mask 100, sothat the mask 100 can move the patient toward or away from the device112 when it is deflated or inflated respectively. For example, FIG. 7 aillustrates a relatively deflated mask 100, with a user relatively closeto the device 112. FIG. 7 b illustrates a relatively inflated mask 100,with the user relatively farther from the mask 100. “Inflating” or“inflated” may include a mask 100 in a fully inflated state, or a mask100 in a less than fully inflated state, but still in a state that ismore inflated relative to a previous state (e.g. a deflated state) or atleast partially inflated. Similarly, “deflating” or “deflated” mayinclude a mask 100 in a fully deflated state, or a mask 100 in a lessthan fully deflated state, but still in a state that is more deflatedrelative to a previous state (e.g. an inflated state) or at leastpartially deflated.

A patient location sensor 166 can be included in order to detect howclose or how far the user is from the medical device 112. If the user isnot at a desired distance from the device 112, the framework 154 on themask 100 can be inflated or deflated to bring the user to the desireddistance. Any variety of sensors 166 can be used to detect the distancebetween the user and the medical device 112, according to sensors knownin the art. In one embodiment, a patient location sensor 166 can beincluded with the medical device 112 in alignment with the user'sforehead, as illustrated in FIGS. 7 a-7 b . Thus, the location sensor166 can measure, for example, the distance or relative distance from theforehead to the medical device 112. In one embodiment, the sensor 166can be a switch, which can be actuated (e.g. activated or depressed)when the user's forehead presses against the switch when the user isclose to the medical device 112. In addition, other types of sensors indifferent locations could measure the distance between the user and themedical device 112. In one embodiment, the location sensor 166 is notplaced on the medical device 112, but is placed in a location that canstill detect the distance between the user and the medical device 112(e.g. on the walls of a room in which the medical device 112 islocated). In one embodiment, the information regarding the distancebetween the user and the medical device 112 is provided by an OCTdevice.

FIG. 8 illustrates a system 174 for controlling, monitoring, andproviding air to the inflatable mask 100. The system 174 can be used tocontrol a patient's distance from the medical device 112, the patient'smovement to and from the medical device 112, the seal between the mask100 and the patient's face, and/or pressure in the ocular cavities 160a, 160 b of the mask 100.

Referring to FIG. 8 , the system 174 can include pumps 176, an airsource 176, conduits 178, valves 182, pressure sensors 188, flow sensors188 and/or processors (not shown). In addition, air into and out of theinflatable chambers 150 a, 150 b and/or cavities 160 a, 160 b can becontrolled by similar components. Referring to FIG. 7 b , the airsource/pump 176, valves 182, sensors 188, and the mask 100 can be influid communication with each other via conduits 178. In addition, theair source/pump 176, valves 182, and sensors 188 can be in electroniccommunication with a processor. Further, the processor can be incommunication with electronics associated with a medical device 112,such as an OCT device.

In some embodiments, the air source/pump 176, conduits 178, valves 182,sensors 188, and processors can be contained within a single unit, suchas a medical device 112. In other embodiments, the components may bespread out across several devices external to a medical device 112.

Referring to FIG. 8 , the mask 100 can be connected to an airsource/pump 176, which can comprise compressed air, ambient air from theenvironment of the mask (e.g. in a clinical room), a reservoir, a sink(e.g. for providing water to the mask 100), an automatic pump, manualpump, hand pump, dispenser, or any other suitable air source/pump.

Valves 182 can also be included in the system 174 for increasing,decreasing, stopping, starting, changing the direction, or otherwiseaffecting the flow of air within the system 174. In some embodiments,the valves 182 can direct air to an exhaust port, in order to vent airin the cavities 160 a, 160 b or inflatable chambers 150 a, 150 b. Insome embodiments, valves 182 are not included in the ports 170 a-b, 180a-b of the mask 100, and are external to the mask 100. In someembodiments, valves 182 can be included in the ports 170 a-b, 180 a-b ofthe mask 100.

In some embodiments, the system can also include an ocular pressuresensor 186 to sense the pressure inside the ocular cavities 160 a, 160b. Readings from the pressure sensor 186 can be used for intraocularpressure and retropulsion measurements. In addition, the system 174 caninclude a chamber pressure sensor 184. In some embodiments, the chamberpressure sensor 184 can be used to determine whether a patient ispressing their face against the mask 100, or how hard the patient ispressing their face against the mask 100.

A flow sensor 188 can also be provided to measure the volume of flowinto and out of the ocular cavities 160 a, 160 b and inflatable chambers150 a, 150 b. Flow sensors 188 may be useful when, for example, theinflatable chamber 150 a, 150 b is underinflated such that the pressureinside the inflatable chamber equals atmospheric pressure. In such acase, pressure sensors 188 may not be useful but a flow sensor 188 canmeasure the volume of fluid pumped into the inflatable chamber 150 a,150 b. In some embodiments, one set of sensors can be provided for theocular cavities 160 a, 160 b, and another set of sensors can be providedfor the inflatable chambers 150 a, 150 b.

Referring to FIG. 8 , the conduits 178 can convey the flow of air (orgas, liquid, gel, etc.) between the pump/air source 176, valves 182,sensors 188, and the mask 100. In some embodiments, the valves 182 canbe downstream of the pump/air source 176, the sensors 188 can bedownstream of the valves 182, and the mask 100 can be downstream of thesensors 188.

In some embodiments, the conduit 178 terminates at conduit ends 192,shown in FIGS. 2 a-2 b . The conduit ends 192 can be designed to couplewith the ports 170 a-b, 180 a-b of the mask 100. Referring to FIGS. 2a-b , in some embodiments, the ports 170 a-b, 180 a-b of the mask 100can include a male portion (e.g. a luer lock taper connector), and theconduit ends 192 can include a female portion.

In some embodiments, the ports 170 a-b, 180 a-b of the mask 100 caninclude a female portion, and the conduit ends 192 can include a maleportion. In addition, the conduit ends 192 and the ports 170 a-b, 180a-b can contain flanges, tubings, or any other mechanism for couplingwith each other. When the ports 170 a-b, 180 a-b are coupled to theconduit ends 192, an air-tight seal for fluid flow between the mask 100and the system can be created.

Referring to FIG. 2 a , in some embodiments, one movement (e.g. pressingthe mask 100 down in the direction of the arrow 199) can connect allfour ports 170 a-b, 180 a-b to the conduit ends 192 at the same time. Insome embodiments, the conduit ends 192 extend to the exterior of themedical device 112, and the conduits 178 can be connected to theexterior ports 170 a-b, 180 a-b one at a time. In some embodiments, theconduits ends 192 are located on the medical device 112, and a separateconduit piece can connect the conduit ends 192 to the external ports 170a-b, 180 a-b.

In some embodiments, the system 174 can be used in clinical settings,such as during a medical visit (e.g. a medical examination). Thecomponents can be utilized in a variety of different ways andcombinations during the medical treatment.

For example, during a medical diagnostic or treatment, referring to FIG.2 a , the mask 100 can be interfaced with the medical device 112 byaligning the ports 170 a-b, 180 a-b of the mask 100 with the conduitends 192 in the medical device 112, and pushing down on the mask 100.

The patient's head can be brought into contact with the rear concavedsurface 122 of the mask 100, and system 174 can inflate or deflate theinflatable chambers 150 a, 150 b, so that the mask 100 conforms to thepatient's face, thereby forming an air-tight seal around the ocularcavities 160 a, 160 b.

During the procedure, the system 174 can change the pressure in theair-tight ocular cavities 160 a, 160 b by a desired amount depending onthe medical examination being taken. The pressure sensor 186 can sensethe amount of pressure in the ocular cavities 160 a, 160 b, and sendthat data to the processor. In addition, the system 174 can vary thepressure in the ocular cavities 160 a, 160 b during the procedure. Forexample, the processor can increase the pump 176 speed or change thevalve state 182 so that flow is restricted.

Other components in the medical device 112 can also take measurements,such as ocular measurements, which can be combined with the data sent bythe pressure sensors. For example, optical imaging components canmeasure changes in curvature or position of the anterior of the eye andin some embodiments, compare those changes to changes in the position orcurvature of posterior of the eye. In addition, changes in the locationsand distances of tissues, such as in the eye, can be imaged based on thepressure in cavities 160 a and 160 b sensed by the pressure sensors.Thus various pieces of data can be analyzed and processed intomeaningful medical information.

Further, during the procedure, the system 174 may receive data from apatient location sensor 166 (see e.g. FIG. 7 a-7 b ) indicating thedistance between the patient and the medical device 112. The processormay determine that the patient should be positioned closer to or fartheraway from the medical device 112, in order to obtain more accurate andprecise readings. Thus, the processor may use the location of thepatient to modulate the inflation or deflation of the mask 100 more orless (e.g. by changing pump speed, changing valve state, etc.), in orderto bring the patient closer to or farther away from the medical device112.

In some embodiments, the processor can switch on the pump/air source 176and open the valves 182 to introduce air into the ocular cavities 160 a,160 b or inflatable chambers 150 a, 150 b according to a preset pressureor flow volume goal. In addition, flow in the system can be reversed todeflate the inflatable chambers 150 a, 150 b.

The mask 100 may include a mechanism for easily identifying a patientaccording to one embodiment. For example, the mask 100 may include anRFID tag, bar code or QR code, or other physical embodiment, to identifythe wearer to other devices. Thus, for example, when a patient with acertain mask 100 nears the medical device 112, the system can determinewho the patient is, and execute instructions tailored for the patient(e.g. how much air is needed to properly inflate the framework 154, howmuch pressure should be applied to the ocular cavities 160 a, 160 b,what readings the medical device 112 should take, etc.)

The mask 100 can be made of a material, such as plastic (e.g.polyethylene, PVC), rubber paper, or any other suitable material. Invarious embodiments, the mask 100 can be configured to be disposable bymaking it out of inexpensive materials such as paper, rubber or plastic.In various embodiments, the mask 100 can be configured to be reusableand easily cleaned either by the wearer or by another person.

In some embodiments, the mask 100 can provide a barrier between thepatient and the medical device 112, increasing cleanliness and servinghygienic purposes.

In one embodiment, the mask 100 can be configured to create a barrier toexternal or ambient light, such as by constructing the mask 100 out ofopaque materials that block light transmission. Accordingly, the mask100 can prevent ambient light from interfering with medical examinationmeasurements, such as optical devices, and ensure the integrity of thosemeasurements.

Although examples are provided with reference to “air” (e.g. introducingair into the inflatable chamber, introducing air into the ocularcavities), it will be appreciated that other substances besides air canbe used, such as gas, fluids, gel, and particulate matter.

Although examples are provided with reference to a mask 100 for abinocular system, it will be appreciated that the embodiments disclosedherein can be adapted for a mono-ocular system. Thus, in one embodiment,the mask 100 includes an inflatable framework 154 defining one cavityinstead of two, and that cavity can form a seal against the periphery ofone eye socket. Further, while examples are provided with reference toeye sockets and eye examinations, it will be appreciated that theembodiments disclosed herein can be used with other tissues and medicalapplications.

In other embodiments, an inflatable device may cover different bodytissues such as gloves for the hands, stockings for the feet or a hatfor the head. In various embodiments, the inflatable device may includea cavity similar to the ocular cavity in the mask and may have at leastone port to provide access to the cavity and change pressure therein orinflow gas therein or outflow gas therefrom, as well as a port toinflate the inflatable devices.

The inflatable mask can be used in a wide variety of clinical settings,including medical examinations and encounters that may be assisted byautomated systems. Various embodiments of an automatic encounter portalare described below.

Electronic Encounter Portal

Medical encounters can be commonly comprised of administrative tasks,collection of examination data, analysis of exam data, and formation ofan assessment and plan by the healthcare provider. In this context, ahealthcare provider may be a licensed healthcare practitioner, such as amedical doctor or optometrist, allowed by law or regulation to providehealthcare services to patients. Examinations may be comprised ofnumerous individual tests or services that provide information for ahealthcare provider to use to make a diagnosis, recommend treatment, andplan follow-up. The data from these tests that are collected for use byhealthcare providers can be broken down into three rough categories:historical data, functional data and physical data.

Historical data can be collected in many ways including as a verbalperson-to-person interview, a written questionnaire read and answered bythe patient, or a set of questions posed by an electronic device eitherverbally or visually. Typical categories of historical information thatare obtained in medical exams can include but are not limited to a chiefcomplaint, history of present illness, past medical history, past ocularhistory, medications, allergies, social history, occupational history,family history, sexual history and a review of systems.

Functional data can be collected through individual tests of functionand can be documented with numbers, symbols or categorical labels.Examples of general medical functions can include but are not limited tomeasurements of blood pressure, pulse, respiratory rate, cognitiveability, gait and coordination. Ophthalmic functions that may be testedduring an exam can include but are not limited to measurements ofvision, refractive error, intraocular pressure, pupillary reactions,visual fields, ocular motility and alignment, ocular sensation,distortion testing, reading speed, contrast sensitivity, stereoacuity,and foveal suppression.

Physical data can capture the physical states of body tissues and can becollected in many forms, including imaging, descriptions or drawings, orother physical measurements. This may be accomplished with simplemeasurement tools such as rulers and scales. It may also be accomplishedwith imaging devices, such as color photography, computed tomography,magnetic resonance imaging, and optical coherence tomography (OCT).Other means to measure physical states are possible. Physicalmeasurements in general medical exams can include height, weight, waistcircumference, hair color, and organ size. Ophthalmic structuralmeasurements can include but are not limited to slit lamp biomicroscopy,retinal OCT, exophthalmometry, biometry, and ultrasound.

Currently, almost all of the individual tests that make up a medicalexamination are conducted by a human laborer often through the operationof a device. Whether this person is a healthcare provider or an alliedhealthcare professional, these laborers can be expensive, can oftenproduce subjective results, and can have limitations on their workingcapacity and efficiency. Given the labor intensive nature of exams,healthcare care practices (which may also be referred to herein as“clinics” or “offices”) and in particular eye care practices oftenemploy numerous ancillary staff members for every healthcare providerand dedicate large areas of office space for waiting rooms, diagnosticequipment rooms and exam rooms. All combined, these overhead costs makehealthcare expensive, inefficient and often prone to errors.

Automation is a well-known way of improving efficiency and capacity aswell as reducing unit costs. Patient-operated or entirely operator-lessdevices may be preferable as labor costs increase and the need forobjective, reproducible, digital, quantitative data increases.

With reference to FIG. 9 , there is illustrated one embodiment of anelectronic encounter portal. The encounter module 200 can be anelectronic device that may be comprised of, for example, data storage,communication, or computer code execution capabilities and may containinformation on patients registered for a healthcare encounter in anoffice.

The office interface 210 can be comprised of software that may be usedby people to interact with the encounter module 200. Other software mayalso be included in the office interface 210. In one embodiment, theoffice interface 210 also can be comprised of an electronic device, suchas a computer, tablet device or smartphone. In various embodiments,office staff can use the office interface 210 to, for example, createrecords or enter patient data into the encounter module 200 for patientswho register in the clinic. This data entry can be enabled in many ways,including for example, manual entry, entry by copying previously-entereddata from an office database 220, or entry using a unique identifierthat can be compared to an office database 220 or external database 230,such as an Internet or cloud-based database, to retrieve pre-entereddata for a patient matching that unique identifier. In one embodiment,registration can be completed with a code, such as an encounter code, ina fashion similar to checking in for an airline flight at an airport.This code could, for example, by linked to patient or providerinformation required for registration purposes.

The office database 220 can be configured to store data from pastencounters, as well as other types of data. The external database 230can be also configured to store at least data from past encounters, aswell as other types of data. The encounter module 200 can be configured,for example, to access, copy, modify, delete and add information, suchas patient data, to and from the office database 220 and externaldatabase 230. The external database 230 can be configured to, forexample, receive, store, retrieve and modify encounter information fromother offices.

In one embodiment, patients may self-register or check into the clinicby using the office interface 210 to, for example, create an encounterrecord, enter encounter information manually, select their informationfrom a pre-populated office database 220, or enter a unique identifierthat can be compared to an office 220 or external database 230 toretrieve their other associated data.

The encounter module 200 can be configured to contain patient recordswhich may also contain clinic processes 205. A clinic process 205 can becomprised of, for example, orders from the healthcare provider for thepatient's care. In one embodiment, the orders may indicate the sequenceof evaluations and care. For example, a provider may indicate that agiven patient should undergo a medical history followed by anexamination with various medical devices followed by an assessment bythe provider.

In one embodiment, the clinic process 205 can be configured to enablealteration of the orders, the order sequence or both the orders andtheir sequence by, for example, office staff or the provider. Examplesof this could include insertion of an educational session about a givendisease prior to a discussion with the provider, deletion of a treatmentdenied by a patient, or switching the sequence of two test procedures.

In some embodiments, the prescribed orders themselves may contain listsof prescribed tests to be performed on a given device. For example, aspart of a technician work-up order, a provider may prescribe bloodpressure and pulse measurement testing to be performed on a patientusing a device in the clinic. The order and prescription of these testsmay change throughout the encounter having been altered by office staff,the provider, or electronic devices.

In one embodiment, a diagnosis or medical history of a patient from theencounter module 200 can be included in the clinic process 205 and maybe used, for example, to determine or alter the clinic process 205. Forexample, a history of past visits and evaluations may alter the teststhat are ordered or the devices that are used during an encounter.

In one embodiment of an electronic encounter portal, a tracking system240 can be configured to enable a component of an electronic encountersystem to determine the physical location or position of, for example,patients, providers and staff in the office space. In one embodiment, acomponent of the electronic encounter system can use data from thetracking system 240 to monitor the progress of patients through a clinicprocess 205. In one embodiment, this tracking system 240 can becomprised of a sensing technology, such as a compass, radiofrequencyantenna, acoustic sensor, imaging sensor, or GPS sensor that determinesthe position of the sensor in relation to known objects such as officewalls, positioning beacons, WiFi transmitters, GPS satellites, magneticfields or personnel outfitted with radiofrequency ID tags.

The tracking system 240 may also be configured to perform mathematicalcalculations, such as triangulation, to analyze signals from thesensors. The tracking system may also compare signals from the sensorsto databases of known signals collected at a prior date, such ascomparing a measured magnetic field to a database of known magneticfields at every position in the clinic. In some embodiments, thistracking system 240 can also be comprised of an emission technology suchas a radiofrequency beacon, to indicate the position of an object in theoffice space.

The tracking system 240 may also be configured to localize the positionof a person or object using a known map of the office space as shown inFIG. 3 . Knowledge of the position of sensors, patients or personnel inan office space map may enable the tracking system 240 to provideinformation to the encounter module 200 regarding the location ofpatients, providers or other office personnel in an office space.

The tracking system 240 can also be configured to provide positioninformation to other components of the electronic encounter system, suchas the office interface 210 or the patient interface 250, eitherdirectly or via an intermediate component such as the encounter module200. An example of how this information might be used is to providestatus information to a user as to the progress or status of otherpeople in the office.

In one embodiment, office personnel can use the office interface 210 tomonitor the location or progress of, for example, providers, staff orpatients within the office space. This monitoring may includecalculation of, for example, time spent in a given location, progressthrough a clinic process 205, or current status of activity, such aswaiting, working or occupied. This monitoring ability can beadvantageous so that office staff can, for example, monitor delays inthe provision of patient care or identify recurrent patient flowbottlenecks that can be reduced through optimization of clinic flow.

The patient interface 250 can be comprised of software that may be usedby patients to interact with the encounter module 200. In oneembodiment, the patient interface 210 can also comprise an electronicdevice, such as a computer, tablet device or smartphone which can besupplied by the clinic or be supplied by the patient. For the purpose ofclarity, in one embodiment, the patient interface 250 may be thepatient's own electronic device, such as a smartphone or computer, thatcan be configured with patient interface 250 software. In otherembodiments, the office interface 210 and the patient interface 250 maybe the same device, such as with a mobile tablet computer or smartphone,that can be configured to allow a patient to perform actions of both anoffice interface 210, such as registration, and actions of a patientinterface 250, such as viewing patient data or asking electronicquestions of office personnel.

The encounter module 200 and the patient interface 250 can be configuredto interface with various devices 260 in the clinic. These devices 260can include but are not limited to diagnostic instruments, such as bloodpressure monitors, imaging devices or other measurement instruments, ortherapeutic devices, such as lasers or injection apparatuses. Theencounter module and the patient interface 250 can be configured to sendand receive data with these devices 260. Communication with thesedevices 260 can be enabled by but is not limited to wired connections,wireless connections and printed methods, such as bar codes or QR codes.

With reference to FIG. 3 , there is illustrated a map of a healthcareoffice. In one embodiment, the patient can register for a healthcareencounter at the office entrance 300. In other embodiments, the patientmay register for a healthcare encounter at a place other than entrance300. In one embodiment, encounter registration can be completed by ahuman receptionist who may enter information into the encounter module200 through the office interface 210. In another embodiment,registration may be completed by the patient for example by using anassisted or self-service kiosk configured with an office interface 210.

A kiosk may, for example, be comprised of a location where an untraineduser can perform a task or tasks, such as checking in for an appointmentor performing a requested test. This kiosk may be comprised ofelectronics or computer equipment, may be shielded from the view ofother people in the same room, may be comprised of seating, and mayprovide a material result to a user. Other kiosk configurations arepossible.

In another embodiment, the patient may register for the encounter withan office interface 210, such as a tablet computer, that is supplied bythe clinic and may have been configured with software to interface withthe encounter module 200. In still another embodiment, the user mayregister for the encounter with their own portable device, such as amobile phone or tablet computer, that can be configured with softwarethat can allow it to act as either or both an office interface 210 or asa patient interface 250.

In various embodiments, orders or steps in an electronic encountersystem can include, for example, asking a patient to sit in waiting area310, asking a patient to proceed to testing area 320 or asking a patientto go to clinic area 330. These orders can be conveyed to the patientby, for example, the patient interface 250 or by office personnel. Inone embodiment, the desired disposition for a patient can be determinedby a clinic process 205 that may have been entered into the encountermodule 200 and communicated to the patient via the patient interface 250or office personnel.

In one embodiment, the patient interface 250 can be configured to useinformation from the tracking system 240 for example, to determine thelocation of the patient in the clinic, to determine the next plannedlocation for a patient from a clinic process 205 in the encounter module200, or to communicate directions to a patient using the patientinterface 250.

Referring to FIG. 10 , in one embodiment 340, a line can be drawn on aschematic map of the clinic space on patient interface 250 to show thepatient how to walk to their next destination in the clinic. In anotherembodiment, the patient interface 250 can be configured to communicatedirections verbally, such as by text-to-speech software.

In one embodiment, the encounter module 200 may be configured to monitorwhich rooms and devices in an office are “in use” based on informationprovided by the tracking system 240. In one embodiment, the encountermodule 200 may be configured to select a next location for a patientbased on which rooms or devices 260 may be free to use. For example, ifthe encounter module 200 determines that a device 260 required for thenext stage of a clinic process 205 is occupied or busy, the encountermodule 200 can be configured to alter the clinic process 205 byinserting, for example, a waiting room order that, for example, can beremoved from the clinic process 205 when the required device is free foruse.

In one embodiment, the encounter module 200 can be configured to monitorutilization of a device 260 or clinic area that may be required for thenext stage of a clinic process 205 and may be configured to insert anorder for a patient to move to that device 260 or clinic area when itbecomes free for use.

In another embodiment, the encounter module 200 can be configured tomonitor the list of patients waiting for a provider and also todetermine which providers have the shortest waiting lists or waitingtimes based on, for example, the number of patients in a waiting patientlist and the average time the provider spends with each patient. Theencounter module 200 can be configured to use this information, forexample, to assign patients to providers with the shortest wait times soas to improve clinic flow. Numerous other embodiments of devicedecisions based on dynamic knowledge of device and space utilizationwithin an office space are possible.

An example of a healthcare encounter is shown in FIG. 11 . In oneembodiment, the first step in the encounter may be registration 400which can be completed, for example, by office staff or by the patientusing, for example, an office interface 210. Encounter registration 400may be comprised of many steps such as signing the patient's name andaddress, presenting identification, verifying insurance status, payingco-payments due prior to the encounter, consenting to be seen by theprovider, consent to privacy regulations or payment of other fees. Inother embodiments, the user may skip registration 400 and may proceed toother steps, such as examination 410.

In one embodiment, one step in an automated healthcare encounter can beverification of the user's identity. This may be accomplished, forexample, as part of registration 400, as part of examination 410, priorto using any device 260, or at other times in the encounter. A mobilepatient interface 250 may be advantageous since it can verify the user'sidentity once and then communicate this identity to, for example, theencounter module 200, to providers, or to subsequent devices usedthroughout the encounter, such as devices 260.

In various embodiments, the patient interface 250 can be configured toverify the user's identity through biometrics, such as throughrecognition of the patient's face, voice, fingerprint or other uniquephysical aspects of the subject. In other embodiments, the patientinterface 250 can be configured to verify the user's identity throughconfirmation of a user's unique data, such as their names, date ofbirth, addresses, mother's maiden name, or answers to questions onlyknown to the user. In another embodiment, the patient interface 250 canbe configured to verify the user's identity through confirmation ofcode, such as a password or secret code known only to the user. In stillanother embodiment, the patient interface 250 can be configured toverify the user's identity through coupling of a device carried only bythe user, such as a key, electronic device, bar code or QR code.

In one embodiment of an electronic healthcare encounter, the user maycomplete the history portion of their examination as part of theiroverall encounter. As discussed previously, in various embodiments, thehistory portion of the encounter can be collected, for example, byoffice staff or by the patient themselves. Office staff may use thepatient interface 250 or the office interface 210 to conduct or enterresults from a patient history. In other embodiments, the patient mayuse the patient interface 250 to complete their own history withoutinteracting with office staff.

In various embodiments, the questions can be configured in a form thatfacilitates responses using written, mouse-based, tablet-based or voiceentry such as multiple choice, true or false, or pull-down menuselections. In other embodiments, the questions may require free entrysuch as by writing, voice dictation, or keyboard entry. In theseexamples, the patient interface 250, the office interface 210 or theencounter module 200 may be configured to interpret electronic forms ofthese inputs, such as electronic writing or voice dictation.

In one embodiment, the history portion of the encounter may be comprisedof a standard series of questions. In another embodiment, the series ofquestions may be based on, for example, a preference specified by theprovider, the patient's diagnosis, the patient's symptoms or some otherunique aspect of the encounter.

In still another embodiment, the history portion of the encounter can becomprised of questions from a database whereby the next question to beasked can be determined, for example, based on an answer to a previousquestion. This dynamically-traversed database of questions may useanswers from a question to determine subsequent questions to ask or todetermine sets of questions to ask based on a tree organization ofquestions in the database. For example, if a patient reports colorvision loss, the system can be configured to add a series of questionsrelated to color vision loss to its list of questions even if they werenot previously included in the set of questions to be asked. In laterquestioning, it the patient reports pain on eye movement, the system canbe configured to add, for example, questions related only to pain on eyemovement or questions related to pain on eye movement and color visionloss. The dynamic allocation of new questions based on answers toprevious questions can be configured such that a provider can allow ordisallow such a feature.

In one embodiment, a dynamically-traversed electronic questionnaire canbe configured to assign priority values to each question so that certainquestions can be asked before other questions. In still anotherembodiment, the system can provide a running count of the total numberof questions to be asked to the patient along with an estimated totaltime to completion. In related embodiments, the system can be configuredto allow users or providers to shorten the questionnaire, such as byexcluding lower priority questions, based on aspects of the dynamicquestionnaire such as it taking too much time or involving too manyquestions and answers.

In another embodiment, the patient interface 250 can be configured toallow the user to change display parameters, such as size, color andfont type, used to display questions with the patient interface 250. Inother embodiments, the patient interface 250 can be configured to readquestions aloud, for example using a text-to-speech system orpre-recorded voices, or to ensure privacy by providing a headphone jackwhere the user can connect headphones.

In one embodiment, the encounter module 200 can be configured to directdevices 260 to perform tests and store results associated with theclinic process 205 and the patient's information contained within theencounter module 200. The encounter module 200 can be configured tocommunicate with these devices 260 using a direct wired connection, suchas a USB, Ethernet or serial connection, a wireless connection, such asBluetooth® or 802.11, an intermediate electronic device, such as a USBkey, memory card or patient interface 250, or a physical codedembodiment such as a bar code or QR code.

In one embodiment, the encounter module 200 or patient interface 250 canbe configured to alter the list of tests requested for an encounterbased on answers to history questions or results from testing on devices260. The encounter module 200 or the patient interface 250 can also beconfigured to direct a device 260 to conduct a new test or tests inaddition to or in place of the old test or tests. Alteration of theclinic process 205 by the encounter module 200 or patient interface 250can be allowed or disallowed by a provider either globally orspecifically, such as based on answers to specific questions orcategories of questions, using, for example, the office interface 210.

In one embodiment, the encounter module 200 or the patient interface 250can be configured to initiate operation of a device 260, such as aninstrument to measure vision. In another embodiment, the encountermodule 200 or the patient interface 250 can be configured to allow theuser to initiate operation of a device 260, such as by saying “ready”,pushing a button or pressing a pedal that may be attached to the patientinterface 250. In still another embodiment, the encounter module 200 orthe patient interface can be configured to allow the user to initiateoperation of the device 260, such as by saying “ready”, pushing a buttonor pressing a pedal, through the device 260.

As discussed previously, the encounter module 200 or the patientinterface 250 can be configured to receive data, such as examinationresults, from devices, such as the tracking system 240, the patientinterface 250 or devices 260. As discussed above, the encounter module200 can be configured to communicate with these other components using,for example, a wired connection, a wireless connection, an intermediateelectronic, or using a physical embodiment.

Collection of data from numerous devices by the patient interface 250 orencounter module 200 can be particularly advantageous by reducingtranscription or sorting errors that can occur when human laborers areinvolved in these processes or by centralizing all encounter data in onelocation.

Various components in the electronic encounter system, such as theencounter module 200, can be configured to compile encounter data into adigital package or packages that can be uploaded to, for example, anelectronic health record system either in the office, such as the officedatabase 220, or outside the office via secure external communication235, transmitted to other individuals on a patient's healthcare team viasecure external communication 235, reviewed directly by the provider ona patient interface 250 or office interface 210, or stored on anaccessible external database 230. The external database 230 can beconfigured to be accessible remotely, such as via the Internet, forexample, to facilitate sharing of exam data between providers or tofacilitate access by the patient to their own healthcare data.

As discussed previously, the encounter module 200 can be configured totrack both patients and clinic personnel using the tracking system 240.The encounter module 200 can be configured to store tracking informationsuch that it, for example, can be viewed or analyzed using an officeinterface 210. By tracking a patient's location over time, the encountermodule 200 can be configured to develop clinic patient flow maps thatmay enable staff to identify both acute and chronic problems with clinicflow. For instance, identification of a patient by the encounter module200 who has been waiting longer than a pre-defined threshold valuestored in a clinic process 205 can alert the staff, for example via anoffice interface 210, to address problems with that patient's encounterthat might be leading to this delay. Identification of chronicbottlenecks and waiting points across numerous encounters can allowpractices to optimize their workflow.

Providers can be tracked in several ways. In one embodiment, mobileoffice interfaces 210 can be configured with tracking systems 240 toidentify the location and identity of providers carrying them. Inanother embodiment, the patient interface 250 can be configured torequire providers to log in whenever they are consulting with a patient.In still another embodiment, the tracking system 240 can be configuredto monitor the location or identity of providers wearing identifiers,such as RFID tags. In other embodiments, the encounter module 200 couldbe configured to communicate updates to patients, such as by using thepatient interface 250, to, for example, estimate the approximate waittimes until the provider sees them or to convey how many patients stillneed to be seen by the provider before they are seen by the provider.

The electronic encounter portal can also be configured to provideentertainment or education to a patient. For example, the patientinterface 250 can be configured to provide Internet access 235, accessto previous encounter records stored on the encounter module 200, oraccess to previous encounter records stored on the external database230. The patient interface 250 can also be configured to provide accessby the patient to educational resources, potentially targeted toward thediagnosis or future treatments for a patient, that may be stored oncomponents such as the encounter module 200. In one embodiment, theprovider can use a patient interface 250 or an office interface 210 toenter orders for an educational program into a clinic process 205.

In another embodiment, the patient interface 250 can be used to inform apatient about clinic resources, such as clinical trials, supportprograms, therapeutic services, restrooms, refreshments, etc. based oninformation stored on the encounter module 200. The encounter module 200can also be configured to direct patients to these resources, such asrestrooms, based on information from the tracking system 240 andrequests from the patients using the patient interface 250. Theencounter module 200 can also be configured to manage communicationsbetween patients, using a patient interface 250 and office staff, suchas by using an office interface 210.

In one embodiment, the patient interface 250 can be configured to storedata from devices and, in an embodiment that is mobile such as a tabletor smartphone, can allow the patient to transport encounter data throughthe clinic process 205 for review by or with the provider. In anotherembodiment, the office interface 210 can be configured to enable data tobe uploaded for review by the provider. Both the patient interface 250and the office interface 210 can be configured to access and use priorvisit data from the encounter module 200 to enhance assessments of apatient's healthcare status. Similarly, both the patient interface 250and the office interface 210 can be configured to access prior data fromthe external database 230 to enhance assessments of a patient'shealthcare status.

In related embodiments, the encounter module 200 and the externaldatabase 230 can be configured to act as common locations for encounterdata that can be accessed by both patients and providers. The externaldatabase 230 can be configured to allow remote access to encounter databy both providers and patients when they are outside of the office.Similarly, the external database 230 can be configured to receive datafrom devices 260 at locations outside of the described office and sharethese results with the encounter module 200 for example, to enableautomated remote healthcare encounters.

In one embodiment of an electronic encounter portal, a check-outprocedure 420 may be the last order or step in a clinic process 205. Invarious embodiments, the office interface 210 or the patient interface250 can be configured to allow providers to enter orders for futureencounters such as testing or therapies. In other embodiments, theoffice interface 210 can be configured to enable the provider to enterbilling information to be submitted for insurance reimbursement ordirectly charged to the patient. In still another embodiment, the officeinterface 210 can be configured to allow the provider to recommend afollow-up interval for the next encounter. In a related embodiment, theoffice interface 210 or the patient interface 250 can be configured toallow the patient to select the best time and data for a follow-upencounter. In another embodiment, the office interface 210 can beconfigured to allow the provider to order educational materials oreducational sessions for the patient that may occur after the encounterconcludes.

Accordingly, various embodiments described herein can reduce the needfor clinic personnel to perform these tasks. In addition, variousembodiments enable users to conduct their own complete eye exams.

Automated Eye Examination

FIG. 12 shows an example of a binocular eye examination system based onoptical coherence tomography. Component 500 may be comprised of the mainelectronics, processors, and logic circuits responsible for control,calculations, and decisions for this optical coherence tomographysystem. Light can be output from light source 502 which may becontrolled at least in part by component 500. The light source may becomprised of a broadband light source such as a superluminescent diodeor tunable laser system. The center wavelength for light source 502 canbe suitable for optical coherence tomography of the eye, such as 840 nm,1060 nm, or 1310 nm. The light source 502 may be electronicallycontrolled so that it can be turned on, off or variably attenuated atvarious frequencies, such as 1 Hz, 100 Hz, 1 kHz, 10 kHz or 100 kHz. Inone embodiment, light from light source 502 can travel throughinterferometer 504, which may be comprised of a Mach Zender or othertype of interferometer, where a k-clock signal can be generated. Thiselectronic signal can be transmitted to electronics on component 500 orother components in the system and can be captured on a data acquisitionsystem or used as a trigger for data capture.

The k-clock signal can be used as a trigger signal for capturing datafrom balanced detectors 518 r and 518 l. Alternatively, the k-clocksignal can be captured as a data channel and processed into a signalsuitable for OCT data capture. This k-clock signal can be captured allof the time, nearly all of the time or at discrete times after which itwould be stored and recalled for use in OCT capture. In someembodiments, various parameters of the k-clock signal, such as frequencyor voltage, can be modified electronically, such as doubled orquadrupled, to enable deeper imaging in eye tissues. In variousembodiments with light sources that sweep in a substantially linearfashion, the k-clock can be removed and a regular trigger signal may beemployed. In various embodiments, the trigger signals used byelectronics 595 r and 595 l may be synchronized with other components ofthe system, such as mirrors, variable focus lenses, air pumps andvalves, pressure sensors and flow sensors.

Most of the light, such as 90% or 95%, that enters the interferometer504 can be transmitted through interferometer 504 to a beam splitter orcoupler 510. As used herein, “coupler” may include splitters as well ascouplers. Beam coupler 510 can split the light from interferometer 504or light source 502 to two output optical paths, specifically right andleft, that lead directly to couplers 515 r and 515 l. Henceforth,designation of a device or component with a suffix of ‘r” or ‘l’ willrefer to two devices that may be of the same type but are located indifferent optical paths. For example, one component may be located inthe optical path of the right eye, designated as ‘r,’ and the other islocated in the optical path of the left eye, designated as ‘l.’

The optical paths in this system may be comprised of fiber optics, freespace optics, a mixture of free space and fiber optics. Othercombinations are also possible. The split ratio of coupler 510 can be apredefined ratio, such as 50/50 or 70/30. Light from coupler 510 cantravel to couplers 515 r and 515 l. Couplers 515 r and 515 l may alsosplit light from coupler 510 with a predefined split ratio such as a50/50, 70/30, or 90/10. The split ratios for couplers 510, 515 r and 515l may be the same or different split ratios.

One portion of light from couplers 515 r and 515 l, such as 70%, cantravel to a so-called ‘reference arm’ for each of the right and leftoptical paths. The reference arm of a light path is distinguished fromthe so-called sample arm of the light path since light in the referencearm of the system does not interface with eye tissue directly whereaslight in the sample arm is intended to contact eye tissue directly.

The main component in the reference arm may be an optical delay device,labeled as 516 r and 516 l in the right and left optical paths of thesystem. Optical delay devices can introduce a delay, such as 1picosecond, 10 picoseconds or 100 picoseconds, into a light path toenable matching of the overall path length of one optical path to theoptical path length of another light path. In various embodiments, thisoptical delay may be adjustable, such as with an adjustable free lightpath between two collimating optical devices, a fiber stretcher thatincreases or decreases the length of a fiber optic, or a fiber Bragggrating that delays light based on changes in the angle of incidence oflight.

In other embodiments, this optical delay line can include variableattenuators to decrease or increase the transmission of light, opticalswitches or mechanical shutters to turn the light off or on. Althoughpictured in the reference arm of this system, an optical delay line canalso be entirely included in the sample arm optical path for each eye orcontained in both the reference and sample arm light paths. Othercombinations of sample and reference light paths are also possible.

In one embodiment, light from optical delay devices 516 r and 516 l cantravel to couplers 517 r and 517 l where it may be combined with lightfrom the sample arm that has been transmitted from couplers 515 r and515 l. Couplers 517 r and 517 l may combine light from two light pathswith a predefined ratio between paths such as a 50/50, 70/30, or 90/10.Light from couplers 517 r and 517 l may travel through two outputs fromcouplers 517 r and 517 l to balanced detectors 518 r and 518 l where thelight signal can be transformed into an electrical signal, for examplethrough the use of photodiodes configured to detect the light input fromcouplers 517 r and 517 l.

The electrical signal generated by balanced detectors 518 r and 518 lcan be in various ranges, including but not limited to −400 mV to +400mV, −1V to +1V, −4V to +4V and have various bandwidths, including butnot limited to 70 MHz, 250 MHz, 1.5 GHz. The electrical signal frombalanced detectors 518 r and 518 l may travel via an electricalconnection, such as a coaxial cable, to electronics 595 r and 595 lwhere it can be captured by a data acquisition system configured tocapture data from balanced detector devices. Although not pictured here,a polarization sensitive optical component can be disposed beforebalanced detectors 518 r and 518 l to split two polarities of light in asingle light path into two optical paths. In this embodiment, twooptical paths leading to balanced detectors 517 r and 517 l would besplit into a total of four optical paths which would lead to twobalanced detectors on each side.

One portion of light from couplers 515 r and 515 l, such as 30% or 50%,can travel to a so-called sample arm of each of the right and leftoptical paths. In various embodiments, the system may be configured totransmit the light through fiber optic cable or through free spaceoptics. Light from couplers 515 r and 515 l can travel to optics 520 rand 520 l which may be collimators configured to collimate the lightfrom couplers 515 r and 515 l. Light from optics 520 r and 520 l cantravel to lens systems 525 r and 525 l which may be comprised of fixedfocus or variable focus lenses.

In various embodiments, these lenses can be fabricated from plastic orglass. In other embodiments, these lenses may be electrowetting lensesor shape-changing lenses, such as fluid-filled lenses, that can varytheir focal distance based on internal or external control mechanisms.In one embodiment, variable focus lenses in lens systems 525 r or 525 lmay have their focal length modified by electrical current or voltageapplied to lens systems 525 r or 525 l. This control may come fromelectrical components 595 r and 595 l and the parameters of this controlmay be based on pre-determined values or may be derived during operationof the system based on input received from other components of thesystem.

The lenses in lens systems 525 r and 525 l can be configured to haveanti-reflective coatings, embedded temperature sensors, or otherassociated circuitry. Lens systems 525 r and 525 l may be comprised of asingle lens or multiple lenses. The lenses comprising systems 525 r and525 l may be present at all times or may be mechanically moved in andout of the light path such as by an attached motor and drive circuitunder electrical control from components 595 r and 595 l. Configurationof lens systems 525 r and 525 l to be moveable can enable imaging atdifferent depths in an eye tissue by introducing and removing vergencein the optical system.

Light from lens systems 525 r and 525 l can travel to movable mirrors530 r and 530 l. Movable mirrors 530 r and 530 l may be comprised ofMEMS (microelectromechanical systems) mirrors, controlled bygalvanometers, or moved by other means. Movable mirrors 530 r and 530 lcan be comprised of a single mirror that reflects light across 2 axes,such as X and Y, can be comprised of a single mirror that reflects lightacross one axis only, or can be comprised of two mirrors that eachreflect light across one axis only said axes being substantiallyperpendicular to each other.

Electrical control of mirrors 530 r and 530 l, which may control eachaxis of reflection independently, can be provided by components 595 rand 595 l. The electronic control of mirrors 530 r and 530 l may beconfigured to enable variable amplitude deflections of mirrors 530 r and530 l. For example, for a given drive frequency in a given axis, thecurrent or voltage applied to mirrors 530 r and 530 l may enable largeror smaller amplitude deflections of the mirror surface, thus creating azoom effect where the created image can be made smaller or larger.

Light that has been reflected from movable mirrors 530 r and 530 l cantravel to lens systems 535 r and 535 l. Lens systems 535 r and 535 l maybe fixed or variable focus lenses that are located in the optical lightpath at all times or only part of the time. Electrical control of lenses535 r and 535 l, can be conducted by components 595 r and 595 l and mayinclude for example moving these lenses in and out of the light path orchanging their focal lengths. Other actions are also possible.

Light from lens systems 535 r and 535 l can travel to optics 540 r and540 l which may be comprised of dichroic mirrors or couplers. Optics 540r and 540 l may be configured to transmit light from lens systems 535 rand 535 l and combine it with light from lens systems 545 r and 545 l.Light from optics 540 r and 540 l can travel to eye pieces 542 r and 542l before being transmitted to the right and left eye tissues.

Eye pieces (or oculars) 542 r and 542 l can be configured asmulti-element lens systems such as Ploessel-type eyepieces, Erfle-typeeyepieces, telescopes or other designs. In some embodiments, optics 540r and 540 l may be configured to be part of or inside of eyepieces 542 rand 542 l. In other embodiments, variable focus lenses orpolarization-sensitive optics and beam splitters can be configuredinside eyepieces 542 r and 542 l to enable wider axial focusing rangesin eye tissues or simultaneous focusing of light from two axiallocations in eye tissues. Eyepieces 542 r and 542 l may be configuredwith optical components without any refractive power, such as opticalwindows, that may be physically attached or separate from the otherlenses in the system.

Light entering the right and left eyes can be reflected back througheach optical path to enable optical coherence tomography. In oneembodiment, the path of backreflected light originating from lightsource 502 can travel from each eye to eyepiece 542 to optics 540 tolens system 535 to movable mirror 530 to lens system 525 to optics 520to coupler 515 to coupler 517 to balanced detector 518. Variouscalculations and logic-based processes can be completed by components595 r and 595 l based on data contained in signals received frombalanced detectors 518 r and 518 l.

As discussed previously, timing of capture of the signals received bycomponents 595 r and 595 l may be controlled by other inputs, such asthe k-clock input, dummy clock input, or other electrical signal.Electronics 500, 595 r, and 595 l may be configured to have digitalsignal processors (DSPs), field-programmable gate arrays (FPGAs), ASICsor other electronics to enable faster, more efficient or substantiallyreal-time processing of signals received by components 595 r and 595 l.Electronics 500, 595 r, and 595 l may be configured with software, suchas a real-time operating system, to enable rapid decisions to be made bysaid components.

In various embodiments not illustrated here, the eye tissues may bereplaced by calibration targets that, for example, occlude theeyepieces, dispose a mirror target at various distances in front of theeyepieces, or provide an open air space for calibration. Electronics 500may be configured to control the introduction of these non-tissuetargets, such as when the eyes are not present in the optical system. Inother embodiments, electronics 500 may be configured to dispose poweredor moveable components of the system to various states, such as “off,”“home,” or “safety” at various times, such as the beginning, middle andend of a test.

Components 595 r and 595 l can also be configured to control lightsources 585 r-588 r and 585 l-588 l which may be comprised of variouslight sources such as for example, laser diodes, light emitting diodes,or superluminescent diodes. In the illustrated embodiment, only fourlight sources 585 r-588 r and 585 l-588 l are shown. In variousembodiments, different numbers of light sources 585 r-588 r and 585l-588 l may be used and different wavelengths of light sources may beused. In one embodiment, one each of a blue-colored, green-colored,red-colored and near infrared diode can be included in the light sourcegroups 585 r-588 r and 585 l-588 l.

In other embodiments, light sources 585 r-588 r and 585 l-588 l may becomprised of tunable light sources capable of producing numerous spectraof light for the purposes of hyperspectral imaging. For example,employing various light sources in the visible spectrum capable ofproducing narrow bands of light centered at characteristic peaks ofabsorption or reflectivity for oxyhemoglobin and deoxyhemoglobin can beused to enable hyperspectral imaging. Similarly, numerous individuallight sources can be used to achieve the same effect as a light sourcewith a tunable wavelength.

These light sources can be configured to be controlled by components 595r and 595 l using, for example, pulse-width modulation, currentmodulation, voltage modulation, or other electrical control means. Inone embodiment, the modulation frequency of at least one light sourcecan be modified to correct for chromatic aberration from the opticsbetween the light sources and the eye. For example, the modulationfrequency of the red channel could be variably increased or decreased indifferent mirror positions to account for lateral chromatic spreadbetween the red light source and other colors such as blue or green.

Light from light sources 585 r-588 r and 585 l-588 l can travel tooptics 580 r-583 r and 580 l-583 l which may, for example, be focusingoptics. Light from optics 580 r-583 r and 580 l-583 l can then travel tooptics 575 r-578 r and 575 l-578 l which may, for example, be focusingoptics. Each path of light can contain a single frequency of light, suchas 450 nm, 515 nm, 532 nm, 630 nm, 840 nm, or 930 nm or multiplefrequencies of light.

Each path of light from light sources 585 r-588 r and 585 l-588 l may bereflected off optics 571 r-574 r and 571 l-574 l which may, for example,be dichroic mirrors or couplers and may be specifically configured toreflect and transmit light based on their position in the optical path.For example, one optic may be configured to transmit light with awavelength less than 500 nm and reflect light with a wavelength greaterthan 500 nm.

Optics 571 r-574 r and 571 l-574 l can be configured to join togetherlight from different light sources 585 r-588 r and 585 l-588 l into asingle, substantially coaxial beam of light that can travel to optics561 r and 561 l. Optics 561 r and 561 l may be dichroic mirrors orcouplers and may be configured to have a pre-defined split ratio oflight entering from different directions or having differentwavelengths, such as 90/10, 50/50, and 10/90.

A portion of light from optics 571 r-574 r and 571 l-574 l can betransmitted through optics 561 r and 561 l to sensors 566 r and 566 lwhich may, for example, be photodiodes or other components capable ofsensing light. Signals from sensors 566 r and 566 l can be configured tobe transmitted along electrical connections between sensor 566 r andelectrical component 595 r on the right side and sensor 566 l andelectrical component 595 l on the left side. In one embodiment, sensors566 r and 566 l can be configured to monitor the total light power beingemitted by light sources 585 r-588 r and 585 l-588 l.

The portion of light reflected off optics 561 r and 561 l from optics571 r-574 and 571 l-574 l can travel to lens systems 560 r and 560 l.Lens systems 560 r and 560 l may be comprised of fixed focus or variablefocus lenses. In various embodiments, these lenses can be fabricatedfrom plastic or glass. In other embodiments, these lenses may beelectrowetting lenses or shape-changing lenses, such as fluid-filledlenses, that may vary their focal distance based on internal or externalcontrol mechanisms.

In one embodiment, variable focus lenses in lens systems 560 r and 560 lmay have their focal length modified by electrical current or voltageapplied to the lens systems. This control may be under the direction ofelectrical components 595 r and 595 l and it may be based onpre-determined values or be derived during operation of the system basedon input received from other components of the system.

The lenses in lens systems 560 r and 560 l can be configured to haveanti-reflective coatings, embedded temperature sensors, or otherassociated circuitry. Lens systems 560 r and 560 l may be comprised of asingle lens or multiple lenses. The lenses comprising systems 560 r and560 l may be present in the light path at all times or may bemechanically moved in and out of the light path by an attached motor anddrive circuit under electrical control from components 595 r and 595 l.Configuration of lens systems 560 r and 560 to be moveable can enableimaging at different depths in an eye tissue by introducing and removingvergence in the optical system.

Light from lens systems 560 r and 560 l can travel to lens systems 555 rand 555 l. In some embodiments, lens systems 555 r and 555 l can belocated in their respective optical paths at all times. In otherembodiments, lens systems 555 r and 55 l may be moved in and out of theoptical paths based on electrical signals from components 595 r and 595l.

Light from lens systems 555 r and 555 l can travel to movable mirrors550 r and 550 l. Movable mirrors 550 r and 550 l may be comprised ofMEMS mirrors, controlled by galvanometers, or moved by other means.Movable mirrors 550 r and 550 l can be comprised of a single mirror thatreflects light across 2 axes, such as X and Y, can be comprised of asingle mirror that reflects light across one axis only, or can becomprised of two mirrors that each reflect light across one axis onlysaid axes being substantially perpendicular to each other.

Electrical control of mirrors 550 r and 550 l, which can control eachaxis of reflection independently, can be provided by components 595 rand 595 l. Mirrors 550 r and 550 l may have one axis of fast resonantmovement, one axis of slow resonant movement, two slow axes of movement,one fast resonant axis and one slow axis of movement, or two fastresonant axes of movement.

The electronic control of mirrors 530 r and 530 l may be configured toenable variable amplitude deflections of mirrors 530 r and 530 l. Forexample, for a given drive frequency in a given axis, the current orvoltage applied to mirrors 530 r and 530 l may enable larger or smalleramplitude deflections of the mirror surface, thus creating a zoom effectwhere the created image can be made smaller or larger.

Light from movable mirrors 550 r and 550 l can travel to lens systems545 r and 545 l. Lens systems 545 r and 545 l may be configured tointroduce variable amounts of optical cylinder power into the opticallight paths. In one embodiment, the magnitude and axis of thecylindrical optical power introduced into the optical paths by lenssystems 545 r and 545 l can be configured to correct an astigmatismpresent in an eye interfacing with this system.

Lens systems 545 r and 545 l can comprised of two cylindrical lensesconfigured to counter-rotate and co-rotate with each other, anelectrically controlled variable focus, liquid filled lens, or othermethod of introducing cylindrical optical power into a light path.Although not illustrated here, lens systems 545 r and 545 l can also belocated between mirrors 530 r and 530 l and optics 540 r and 540 l inthe OCT light path.

Light from lens systems 545 r and 545 l can travel to optics 540 r and540 l where it may be reflected to combine with light originating atlight source 502. In one embodiment, an exit pupil expander can bedisposed between moveable mirrors 550 r and 550 l and the eye tissues toincrease the size of the exit pupil created at the eye tissue by mirrors550 r and 550 l.

Light from lens systems 545 r and 545 l may be transmitted througheyepieces 542 r and 542 l after which it may enter the right and lefteyes of a subject. Light transmitted through eyepieces 542 r and 542 lcan be configured to be seen by the subject as organized light, such asin a retinal scanning display system, can be configured to be seen bythe subject as video-rate imaging through modulation of light sources585 r-588 r and 585 l-588 l by components 595 r and 595 l, or can beconfigured to broadly stimulate the eye with light such as formeasurements of pupillary reactions to light stimuli.

Light from lens systems 545 r and 545 l can also be configured toreflect back out of the eye and through eyepieces 542 r and 542 l, offoptics 540 r and 540 l, through lenses systems 545 r and 545 l, offmoveable mirrors 550 r and 550 l, through lens systems 555 r, 555 l, 560r, and 560 l and then through optics 561 r and 561 l. Light transmittedthrough optics 561 r and 561 l can be detected by sensors 567 r-570 rand 567 l-570 l which may, for example, be comprised of photodiodes.

In various embodiments, this light is split into predefined wavelengthbands, such as 440 nm-460 nm, 510 nm-580 nm, 625 nm-635 nm, or 930 nm,by dichroic mirrors 562 r-565 r and 562 l-565 l. In other embodiments,separation of light from optics 561 r and 561 l into bands can beachieved by the use of filters that selectively transmit or reflectwavelength bands of interest.

In still other embodiments, separation of light from optics 561 r and561 l into bands can be achieved by configuring the system with sensors567 r-570 r and 567 l-570 l that only produce electrical signals inspecifically targeted bands, such as 400-500 nm, 600-800 nm or >900 nm.Electrical signals from sensors 567 r-570 r and 567 l-570 l can travelto components 595 r and 595 l across electrical connections to enableimaging of tissues in the eye by sensing the light originating at lightsources 585 r-588 r and 585 l-588 l backreflected in desired wavelengthbands.

FIG. 13 shows an example of a display of eye examination data on anelectronic device 600. In some embodiments, the display system enablesviewing and comparing of data from two eyes of one patient acrossmultiple tests and dates in a minimal amount of space. Accordingly, someembodiments enable the user to collapse undesirable test or date fieldsso as to maximize the display area of desired measurements.

Device 600 may be a portable computing platform, such as a smartphone ora tablet, or be a stationary computing platform with a display screen.Device 600 may allow touch screen operation, eye tracking operationwhere eye movements are interpreted as cursor movements on the device600 itself or operation with standard computing peripherals such as amouse and keyboard.

Data in the illustrated grid can be populated by software from adatabase of examination data that may, for example, include exams frommany patients on many days. Accordingly, software running on device 600can be configured to enable searching or selection of the patient whoseexam data is to be displayed in the illustrated display configuration.

Software on device 600 can be configured to output exam data in asubstantially tabular format comprised mainly of rows 612 and columns614. In various embodiments, the software can be configured to includeall exam data for a given date in one column 614 while all measurementsfrom a given test can be included in a single row 612. The software canalso enable preferences that allow transformation of this rule such thatdates are in rows 612 and tests are in columns 614. In some embodiments,each box in the table representing an intersection of a row 612 and acolumn 614 can be represented as a field populated with, for example, anumerical measurement, a text value or an image. Although the fields arelabeled generically in FIG. 6 , it will be appreciated that a variety ofdata, such as numbers, text or images, can be displayed in each field.

Field 610 can be configured to contain information on the patient, suchas name, date of birth, medical record number, age, gender. Although notillustrated here, field 610 may also be used to open pop-up windows thatcan be used to search or configure the exam display system.

Fields 620-625 can be configured to contain dates of exams for a givenpatient. In one embodiment, clicking of a column heading 620-625 togglesthe column between collapsed and expanded configurations where data isnot displayed in the collapsed configuration but data is displayed inthe expanded configuration. In FIG. 6 , columns 620, 623 and 625demonstrate expanded fields while columns 621, 622 and 624 representcollapsed fields. Thus, the fields in the collapsed columns 621, 622,624 may be collapsed. For example, fields 650, 651, 652, 653, 654 may becollapsed when column 621 is collapsed. The software can be configuredto allow users to toggle this display setting with, for example, asimple click of a column heading or other selection process.

Fields 630-634 can be configured to contain individual tests conductedon a given patient. In one embodiment, clicking of a row heading 630-634toggles the row between collapsed and expanded configurations where datais not displayed in the collapsed configuration but data is displayed inthe expanded configuration. In FIG. 6 , rows 63 land 634 demonstrateexpanded fields while rows 630, 632 and 633 represent collapsed fields.Thus, the fields in the collapsed rows 630, 632, 633 may be collapsed.For example, fields 640, 650, 660, 670, 680, and 690 may be collapsedwhen row 630 is collapsed. The software can be configured to allow usersto toggle this display setting with, for example, a simple click of arow heading or other selection process.

In FIG. 13 , it can be appreciated that two special rows can existcorresponding to the right (OD) and left (OS) eye headings. The softwarecan be configured to collapse or expand all tests for a given eye whenthat row heading, such as OD or OS, is clicked or otherwise selected.

Referring to FIG. 13 , fields 641, 644, 671, 674, 691, and 694 can beconfigured to display data, such as numbers, text or images. In oneembodiment, display of images in these fields enables the user to clickon the images to bring up a larger window in which to view the images.In another embodiment, display of numbers in these fields enables theuser to click on the numbers to bring up a graph of the numbers, such asgraph over time with the dates in the column headers as the x-axis andthe values in the rows as the y values.

The software can be configured to show collapsed fields (e.g. field 640,650, 660, 651, 661) in a different color or in a different size. Thesoftware can also be configured to display scroll bars when fieldsextend off the display screen. For example, if more tests exist in thevertical direction than can be displayed on a single screen, thesoftware can be configured to allow panning with finger movements orscrolling with, for example, vertical scroll bars. The software can beconfigured to enable similar capabilities in the horizontal direction aswell.

As described above, in some embodiments, a mask 100 is configured to beinterfaced with an ophthalmic device for performing an eye exam on apatient. In some embodiments, the ophthalmic device comprises an opticalcoherence tomography (OCT) device such as described above. An OCT deviceis operable to direct an incident light beam onto a patient's eye andreceive a reflected or scattered light beam from the patient's retina.Three-dimensional images of eye tissue, such as the cornea, iris, lens,vitreous or retina may be obtained by measuring reflected or scatteredlight from the tissue for example using Optical Coherence Tomography orother instruments. Many OCT devices employ beam-steering mirrors, suchas mirror galvanometers or MEMS mirrors, to direct the light beam to anobject of interest. Various OCT instruments comprise interferometersincluding light sources and optical detectors or sensors that receivelight reflected or scattered from the eye and produce a signal usefulfor imaging the eye. One example of an OCT device is described abovewith reference to FIG. 12 .

When the mask 100 is interfaced with an OCT device for performing an eyeexam, an incident light beam is transmitted through at least one of theoptically transparent sections 124 of the mask 100 before impinging onthe retina of the eye. A portion of the incident light beam may bereflected by the optically transparent sections 124 of the mask. Suchreflection is undesirable as it decreases the amount of lighttransmitted to the retina of the eye and the reflected portion of theincident light beam may also reach the OCT device (e.g., the opticaldetector 518 therein) and may obscure the signal of interest, namely thereflected or scattered light from the retina. In some embodiments, toameliorate this problem, the optically transparent sections 124 of themask 100 are coated with an anti-reflective coating configured to reducereflection of the incident light beam by the optically transparentsections 124. In various embodiments, the optical transparent sections124 of the mask are configured to increase or maximize transmission oflight, such as from an OCT device, and the proximal portions 154 andconcaved rear surface 122 is configured to reduce or minimizetransmission of light, such as ambient light or light not emanating froman OCT machine and may be opaque and include opaque sides. For example,the proximal portions 154 may have sides that are substantiallynon-transmissive to visible wavelengths. These sides may for exampleblock 80-90%, 90-95%, 95-99%, and/or 99-100% of ambient visible light.Reduction of ambient light may for example assist in keeping thepatients pupils dilated. Conversely, the optically transparent sectionsmay have a transmittance of 70-80%, 80-90%, 90-95%, 95-99%, and/or99-99.5%, or 99.5%-100% or any combination of these ranges in thewavelength range at which the ophthalmic device operates such as at 450nm, 515 nm, 532 nm, 630 nm, 840 nm, 930 nm, 1060 nm, 1310 nm or anycombination thereof or across the visible wavelength range, near IRwavelength range, or both these ranges or at least 10%, 20%, 30%, 40%,50%, 60%, 70%, 80%, or 90% of the visible range, near IR range, or both.In some embodiments, material (treated or untreated) such as plasticthat is not substantially transparent to visible light or to manyvisible wavelengths but is transparent to infrared light may beemployed, for example, as the window to the mask and possibly for atleast part of the proximal portion (e.g., the sides). The window wouldthus potentially be able to transmit an IR probe beam from theophthalmic device (e.g., OCT or SLO instrument) yet could block ambientvisible light or a significant portion thereof thereby allowing theuser's pupils when wearing the mask to be more dilated. In variousembodiments, however, having a window having at least some wavelengthsin the visible be transmitted through is useful for the wearer. Incertain embodiments, the ophthalmic device operates at one or more nearinfrared wavelength. For example, the probe beam is in the nearinfrared. The window may therefore be transparent in at least at the NIRwavelength(s) at which the ophthalmic device operate, for example, atthe probe wavelength. Optical coatings may be employed to impart thesespectral characteristics on the mask (e.g., on the window).

In some embodiments, the anti-reflective coating is configured to reducereflection of the incident light beam in a wavelength range that iscomparable to the wavelength range of the light source used in the OCTdevice. For example, wide-spectrum sources such as superluminescentdiodes, ultrashort pulsed lasers, swept source lasers, very shortexternal cavity lasers, vertical cavity surface emitting lasers, andsupercontinuum lasers can be used in OCT devices and could be used inother ophthalmic diagnostic and/or treatment devices. These lightsources may operate in the visible and/or near infrared. For example,light sources that emit light in visible wavelengths such as blue,green, red, near infrared or 400-1500 nm may be used to image the eye.Accordingly, in some embodiments, the anti-reflective coating isconfigured to reduce reflection of the incident light beam in awavelength range that is comparable to a visible spectrum. In someembodiments, the anti-reflective coating spans both a visible andinvisible wavelength spectrum, operating at wavelengths such as 400 nmto 1500 nm, 450 nm to 1150 nm, 515 nm to 1100 nm or other regions. Theanti-reflective coating may be strongly wavelength dependent or may belargely wavelength independent. Likewise, the anti-reflective coatingmay reduce reflection over a wide or narrow band. In some embodiments,the anti-reflective coating is configured to reduce reflection of theincident light beam in a wavelength band having a bandwidth ranging fromabout 5 nm to about 200 nm. In some embodiments, for example, thisbandwidth may be between about 5 and 50 nm, 50 and 100 nm, 100 and 150nm, 150 and 200 nm, 200 and 250 nm or larger. In some embodiments, theAR coating may operate across multiple bands that are separated fromeach other. Each of these bands may, for example, have a bandwidth, forexample, as described above. The antireflective coating may reducereflections at a normal incident angle to between about 5-10%, 3-5%,1-3% or less. For example, with the anti-reflective coating, reflectionsat a normal incident angle may be reduced to 1 to 2% reflection, 0.5% to1% reflection or 0.1% to 0.5% reflection, or 0.05% to 0.5% reflection,or 0.1% to 0.5% reflection, 0.1% to 0.01% reflection, or combinationsthereof. In some embodiments, the amount of reflection may be higher orlower. In various embodiments, the anti-reflective coating operates onlight from normal incidence up to oblique angles of incidence such as±15 degrees, ±30 degrees or ±45 degrees.

The anti-reflective coating may comprise a multi-stack optical structureand, in particular, may comprise an interference coating such as aquarter-wave stack. The anti-reflective coating may comprise, forexample, one or more layers having a thickness of a quarter or halfwavelength of the light and accomplish reflection reduction throughdestructive interference. Other types of anti-reflection coatings may beemployed.

FIG. 14 illustrates a mask 200 for performing an eye exam according toan embodiment. The mask 200 includes a distal sheet member (distalportion) 218 and a proximal member (proximal portion) 254 coupled to thedistal portion 218. The distal portion 218 has one or more substantiallyoptically transparent sections 224. The proximal portion 254 has a rearsurface 222 that faces the patient's face when in use, and is configuredto conform to contours of the patient's face and align the one or moresubstantially optically transparent sections 224 of the distal portion218 with the patient's eyes. The distal portion 218 can be configured tobe optically interfaced with a docking portion of an ophthalmic devicesuch as an OCT instrument. The ophthalmic device is operable to directan incident light beam such as a probe beam onto and/or into a patient'seye and receive a reflected or scattered light beam from the patient'seye. The docking portion of the ophthalmic device includes an opticalinterface such an optically transparent window or plate for transmittingthe incident light beam therethrough and incident on the opticallytransparent sections 224 of the distal portion 218. The docking portionmay also include a slot in which a flange on the mask fits into. In someembodiments, the ophthalmic device comprises an optical coherencetomography device although the ophthalmic device may comprise otherdiagnostic instruments or devices such as a scanning laserophthalmoscope (SLO).

In some embodiments, to reduce retro-reflection back into the ophthalmicdevice, at least one of the optically transparent sections 224 of themask has at least a portion thereof that is tilted or sloped withrespect to the incident light beam when the distal sheet member 218 isoptically interfaced with the docking portion of the ophthalmic device.In such embodiments the incident light beam forms a finite (non-zero)angle of incidence with respect to the corresponding portion of themask. If the finite angle of incidence is sufficiently large, aretro-reflected light beam may be prevented from being retro-reflectedback into the oculars of the ophthalmic device. In some embodiments, themagnitude of the tilt or slope angle is in a range from about 1 degreeto about 30 degrees. In some embodiments, the magnitude of the tilt orslope angle is greater than about 1 degrees, 2 degrees, 4 degrees, 5degrees, 6 degrees, 8 degrees, 10 degrees, 15 degrees, 20 degrees, 25degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, or55 degrees, and less than 60 degrees, 55 degrees, 50 degrees, 45degrees, 40 degrees, 35 degrees, 30 degrees, 25 degrees, 20 degrees, 15degrees, 10 degrees, or 5 degrees or any combination thereof. Forexample, the magnitude of the slope may be greater in magnitude than 30°and less than 35° or greater than 1° in certain portions and less than35° or 40°. This tilt or slope angle may be measured between a centralaxis through the optical path from the ophthalmic device (e.g., OCTinstrument) to the mask and the normal to the surface of the opticallytransparent section 224 of the mask where that central axis or probebeam is incident. In some embodiments, this angle may be measured, forexample, with respect to the optical path from the ophthalmic device(e.g., OCT or SLO instrument) or optical axis of the ophthalmic devices,for example, from the exit pupil of left or right channel of the OCT orSLO instrument, an optical axis of an optical element (e.g., left and/orright ocular lens, eyepiece, or channel) associated with an ophthalmicdevice through which the beam passes prior to output from the ophthalmicdevices, as well as from a normal to a transparent interface (e.g., awindow or ocular lens) on the ophthalmic device. Also this angle may bemeasured with respect to the normal to the surface on the opticallytransparent section 224 of the mask where the beam or center thereof orcentral axis therethrough from the ophthalmic instrument would beincident on the optically transparent section 224. Similarly, this anglemay be measured with respect to the mask's forward line of sight whenworn or the line of sight of a wearer of the mask. A standard anatomicalheadform such as an Alderson headform may be used to determine theline-of-sight through the mask. Accordingly, the angular rangesdescribed above may be measured between the line-of-sight of a Aldersonheadform when the mask is placed on the headform as would be worn by awearer (in the as worn position) and the normal to the surface of theoptically transparent section 224 of the mask at the location that thenormal line-of-sight of the headform intersects or passes. Otherapproaches to measuring the angle may also be used.

In various embodiments, the shape of the rear surface 222 is determinedfrom measurements taken from at least one magnetic resonance imaging(MRI) scan of a human head. Segmentation of the surface of one or morefaces (e.g., at least 10, 20, 30, 100, to 200, 500, 1000, or more faces)obtained from MRI images can be used to determine a contour that issubstantially conformed to by the rear surface 222. Statisticalprocesses can be applied to these sets of MRI images to produce averageface contours, median face contours, or face contours that match acertain percentage of the population, such as 95%, 99%, or 99.5%. TheseMRI images can also be used to define the line-of-sight through themask. Standard lines defined by MRI images of the human head, such asthe eye-ear line extending from the center of the ear canal to thelateral canthus where the eyelids join or a line in the Frankfurt planeextending from the center of the ear to the lowest portion of the eyesocket, can be used to define the direction of the line-of-sight throughthe mask with a rear surface 222 defined by these same MRI images. Otherlines, such as a line that connects the pupillary center and macularcenter as seen by MRI could also be used. The placement of theline-of-sight on the optical transparent section 224 may also be definedby measuring the distance between the pupils, the interpupillarydistance (IPD), on the MRI images.

In various embodiments, the probe beam raster scanned across the tissueto obtain OCT signals over a region of the eye. As described above, toaccomplish such raster scanning, the direction of the probe beam may beswept using, for example, a MEMS mirror. FIG. 15A illustrate anarrangement where a probe beam is reflected off a beam steering mirrorthrough the mask window into the eye. The beam steering mirror can berotate back an forth to sweep the beam through a range of angles andthrough a range of positions in and/or on the tissue being images orevaluated. FIG. 15A show both the optical path of the probe beam as wellfor light scattered from the tissue that returns back through the OCTinstrument. As discussed above, in some instances, reflections from themask window are retro-reflected and thus also return to the sensors usedin the OCT instrument. With the normal to the window oriented at 0° withrespect to the incident probe beam, light is reflected from the windowback into the OCT instrument as shown in FIG. 15A. This retro-reflectedlight introduces noise into the signal comprising scatters light fromthe tissue which could be a weak signal. The back reflection thusdecreases the signal to noise ratio and makes obtaining an image moredifficult.

To improve the signal to noise ratio, the window can be tilted an anglewith respect to the beam. This tilt angle may be β degrees. The resultis that the retro-reflected beam will be tilted such that the beamcannot enter back into the OCT instrument disrupting the signal. Asillustrated in FIG. 15B, for a given ophthalmic instrument such as anOCT instrument, there is an angle, Δ, of the retro-reflected beam(measured with respect to the incident beam or the incident opticalpath) at which the reflected beam is unlikely to enter back into the OCTinstrument and introduce noise onto the OCT signal. This angle Δ maydepend in part on the beam size, the size of the optics in the OCTinstrument, e.g., the beam steering mirror, as well as the relativelocation of the optics longitudinally along the optical path. This anglemay be for example, 0.5° to 1°, 1° to 2°, 2° to 3°, or combinationsthereof.

In various embodiments, as illustrated in FIG. 15C, the optics in theophthalmic instrument are configured such that rays of light from theprobe beam exiting the exit pupil or ocular of the ophthalmic instrumentare generally converging. For example, the probe beam may substantiallyfill the exit pupil of the ophthalmic instrument and be focused down.Such approach may be referred to as a flood illumination. Also, asdescribed above, in some embodiments, a beam having a beamwidth narrowerthan the aperture of the ocular or exit pupil of the ophthalmicinstrument is swept through a range of angles. This approach may bereferred to as beam steering. In both cases light rays may be incidenton the mask at a range of angles, for example, defined by a cone angle(a). This range of angles may be determined, for example, by theF-number or numerical aperture of the output of ophthalmic device suchas the ocular lens or focusing lens of the ophthalmic device and/or bythe movable mirror (MEMS mirror). This range of angles may alsocorrespond to the range of angles that the ophthalmic device willcollect light. For example, rays of light reflected back into this rangeof angles, may be collected by the ophthalmic instrument and contributeto the signal received. This collection angle may also be determined bythe F-number or numerical aperture of the ocular of the ophthalmicdevice (e.g., OCT instrument).

In some embodiments, the tilt or slope angle of the opticallytransparent section 224 of the mask is configured to be greater than thelargest angle of incident light produced by the OCT or other imaging orophthalmic device. For example, if an accompanying ophthalmic (e.g.,OCT) device, because of beam steering or flood illumination, produceslight rays between −30 degrees and +30 degrees with respect to theoptical axis of the ophthalmic device or with respect to the centralaxis of the optical path from the ophthalmic device to the mask (e.g., acone angle α of 30°), the magnitude of the tilt or slope angle (β) ofthe optically transparent section 224 of the mask can in variousembodiments be greater than the cone angle, for example, more negativethan −30 degrees or more positive than +30 degrees. For example, thetilt or slope angle, β, may be less than −30° (e.g., −31°, −32° etc.) orgreater than +30° (e.g., 31° or more).

FIGS. 15C-15E show how tilting the optically transparent section 224reduces the likelihood that light exiting the ophthalmic device will beretro-reflected back into the ophthalmic device.

FIG. 15C, for example schematically illustrates a planar window 224 onthe mask corresponding to the optically transparent section 224 thatdoes not have an AR coating. The window 224 is shown receiving a bundleof rays 265 of light that are focused down by a focusing lens 270 at theoutput of the ophthalmic device. This focusing element 270 may be a lens(e.g., in an ocular) that outputs a focused beam of light from theophthalmic device (e.g., OCT instrument). The focused bundle of rays 265is show centered about a central axis 267 of the optical path from theophthalmic device to the mask that corresponds to an optical axis 267 ofthe ophthalmic device (e.g., the optical axis of the focusing lens 270).The focused bundle of rays 265 may correspond to rays of lightsimultaneously provided with flood illumination or rays of light sweepthrough the range of angles over a period of time by the beam steeringoptics (e.g., movable mirror). FIG. 15C illustrate how, in either case,the bundle of rays 265 propagating along the optical path from theophthalmic instrument to the eye can be reflected back toward theophthalmic device at an angle within the collection angle defined by thenumerical aperture of the lens 270 such that this light would propagateback along the same path to the ophthalmic device and re-enter theophthalmic device possibly interfering with the signal.

FIG. 15D, for example schematically illustrates a planar window 224 onthe mask having an AR coating thereon. Accordingly, the rays of lightreflected from the mask window 224 are shown attenuated as backreflection is reduced by the AR coating.

FIG. 15E, for example schematically illustrates a planar window 224 onthe mask without an AR coating that is tilted or sloped such that thenormal (shown by dotted line) to the window is disposed at an angle, β,with respect to the central axis 267 of the optical axis from the exitpupil or ocular/eyepiece of the ophthalmic device to the window. Themask window receives a bundle of rays 265 of light (eithersimultaneously during flood illumination or more sequentially in a beamsteering approach) focused down by a focusing lens 270 at the output ofthe ophthalmic device. The maximum ray angle or cone angle of thefocused bundle of rays 265 is shown as α. In this example, |β|>α, whereα is the cone angle measured as a half angle as shown. In variousembodiments, |β|−Δ>α. As discussed above, Δ is the angle at which theprobe beam can be offset with respect to the probe optical path so asnot to be coupled back into the OCT instrument via retro-reflection andthereby disrupt the OCT signal by introducing noise. (See FIG. 15B.)Accordingly, rays in the bundle of rays 265 propagating along theoptical path from the ophthalmic instrument to the eye are not reflectedback toward the ophthalmic device at an angle within the collectionangle defined by the numerical aperture of the lens 270 such that thislight does not re-enter the ophthalmic device. Tilting or sloping thewindow 224 sufficiently beyond the angle of the steepest ray of lightfrom the probe beam can reduce retro-reflection. As discussed above, invarious embodiments, the magnitude of the tilt or slope angle β islarger than the cone angle α, where α is the cone angle measured as ahalf angle as shown and is a positive value, or the magnitude of thetilt or slope exceeds the angle of the ray 268 exiting the ophthalmicdevice (e.g., exiting the ocular lens 270 shown in FIG. 15E) that isincident onto the mask window at the largest angle providing greaterdeflection away from the optical axis 267 for that ray 268. Accordinglyin various embodiments, |β|>α thereby increasing the amount of rays thatare not retro-reflected back through the lens 270 and into theophthalmic device. As discussed above, in various embodiments, |β|exceeds α by at least Δ. The magnitude of the tilt or slope angle β ofthe optically transparent section 224 may thus be greater than the coneangle α established by the f-number or numerical aperture of theophthalmic device. In some embodiments, one or more of theserelationships are true for 50-60%, 60-70%, 70-80%, 80-90%, 90-95%,95-98%, 98-99%, or 99-100% of the light from the probe beam (e.g., asrays are swept through the range of angles to provide raster scanning).Combinations of these ranges are also possible.

In addition to being tilted or sloped, the optically transparentsections 224 may also be coated with an anti-reflective coating asdescribed above. In some embodiments, the respective portion of theoptically transparent sections 224 is tilted or sloping upward ordownward, as illustrated in FIGS. 14A-D. In other embodiments, therespective portion of the optically transparent sections 224 is tiltedor sloped temporally or nasally, or in a combination of upward/downwardand nasal/temporal directions.

FIGS. 16A-D illustrate a mask 300 for performing an eye exam accordingto an embodiment. The mask 300 is similar to the mask 200 shown in FIG.14 , except that two of the one or more substantially opticallytransparent sections 224 a and 224 b are tilted or sloped temporally ornasally in opposite directions with respect to each other. In anembodiment, the two substantially optically transparent sections 224 aand 224 b are tilted or sloped symmetrically away from the nose andnasal lines or centerline. In other embodiments, combinations of tiltdirections are possible. For example, according to some embodiments, oneoptically transparent section 224 a is tilted or sloped upward ordownward, and the other optically transparent section 224 b is tilted orsloped nasally or temporally. In some embodiments, a portion of theoptically transparent sections 224 that intersect the incident lightbeam is planar, as illustrated in FIGS. 14 and 15 . In otherembodiments, a portion of the optically transparent sections 224 iscurved, as discussed below.

FIGS. 17A-17C, for example, illustrate how curved windows 224 can beused as the optically transparent sections 224 of a mask and the effectof such curved windows on an incident probe beam 265. In certainembodiments, depending on the placement of the incident beam 265 withrespect to the mask window 224, the window may provide a perpendicularsurface for many of the rays of light in the beam thereby causingretro-reflection back into the channels of the ophthalmic instrumentthereby contributing to noise in the signal.

FIG. 17A, for example, shows a curved window 224 without an AR coatinghaving a center of curvature 272 that is located at the focus point 274of the optics 270 of the ophthalmic device. Such alignment can cause asignificant portion of the light to be retro-reflected back into theophthalmic device. The focus point 274 of the optics 270 in theophthalmic device may comprise the focal point of the lens or optics inthe ophthalmic system (e.g., in the ocular or eyepiece or left or rightoutput channel).

FIG. 17B shows a curved window 224 without AR coating having a center ofcurvature of the window that is behind or beyond the focus point of thelens 270. This positioning may be determined in part by the mask and theinterconnection between the mask and the ophthalmic device thatestablishes the spacing between the ophthalmic device and the eye of thesubject wearing the mask. In FIG. 17B, rays of light are retro-reflectedback toward the ophthalmic device at an angle within the collectionangle defined by the numerical aperture of the lens 270 such that thislight re-enters the ophthalmic device.

In contrast, FIG. 17C shows a curved window 224 without AR coatinghaving the center of curvature that is in front of the focal point 274of the optics. As discussed above, this positioning may be determined inpart by the mask and the interconnection between the mask and theophthalmic device that establishes the spacing between the ophthalmicdevice and the eye of the subject wearing the mask. Some of the rays onthe outer parts of the cone of rays 265, including the ray 268 directedat the largest angle are not retro-reflected back toward the ophthalmicdevice at an angle within the collection angle defined by the numericalaperture of the optics 270 such that this light does not re-enter theophthalmic device. However, rays closer to the optical axis 267 arecloser to being perpendicular with the normal of the window such thatthose rays are retro-reflected back toward the ophthalmic device at anangle within the collection angle defined by the numerical aperture ofthe optic 270 and thus re-enter the ophthalmic device. In variousembodiments where the ophthalmic device is a beam-scanning device suchas an OCT device or a scanning laser ophthalmoscope, a small offsetangle between the cone of rays 265 and the slope of the curved window224 is sufficient to sufficiently reduce or prevent retro-reflection oflight into the ophthalmic device.

FIGS. 17D and 17E schematically illustrate shifts of the center ofcurvature of the window to the left and the right. FIG. 17D shows acurved window 224 without AR coating having a center of curvature of thewindow that is to the left of the focus point and optical axis 267 ofthe lens 270. This positioning may be determined in part by the mask andthe interconnection between the mask and the ophthalmic device thatestablishes the spacing and positioning between the ophthalmic deviceand the mask as well as the eye of the subject wearing the mask. In FIG.17D, rays of light that intersect the curved window 224 to the right ofits center of curvature are retro-reflected at an angle that issubstantially directed away from the lens 270 and the optical axis 267.Light that intersects the window 224 to the left of its center ofcurvature is retro-reflected back toward the ophthalmic device at anangle within the collection angle defined by the numerical aperture ofthe lens 270 such that this light re-enters the ophthalmic device.

Similarly FIG. 17E shows a curved window 224 without AR coating having acenter of curvature of the window that is to the right of the focuspoint and optical axis 267 of the lens 270. As discussed above, thispositioning may be determined in part by the mask and theinterconnection between the mask and the ophthalmic device thatestablishes the spacing and positioning between the ophthalmic deviceand the mask as well as the eye of the subject wearing the mask. In FIG.17E, rays of light that intersect the curved window 224 to the left ofits center of curvature are retro-reflected at an angle that issubstantially directed away from the lens 270 and the optical axis 267.Light that intersects the window 224 to the right of its center ofcurvature is retro-reflected back toward the ophthalmic device at anangle within the collection angle defined by the numerical aperture ofthe lens 270 such that this light re-enters the ophthalmic device.

In these examples the windows 224 are spherical. In other embodiments,however, the window 224 may have a curved surface other than spherical,e.g., aspheric surface curvature. In addition to being tilted or sloped,the curved optically transparent sections 224 may also be coated with ananti-reflective coating as described above.

FIGS. 18A-D illustrate a mask 300 for performing an eye exam similar tothe mask 200 shown in FIG. 14 , except that two of the one or moresubstantially optically transparent sections 224 a and 224 b are curved.In particular, the substantially optically transparent sections 224 aand 224 b have outer surfaces as seen from the front of the mask havinga convex shape. These curved surfaces may be spherical in shape or maybe aspherical. For example, the curved surfaces may be an ellipsoidalsurface or an oblate spheroid surface, or have a shape characterized bya higher order polynomial or be combinations thereof. Other shapes arepossible. In various embodiments, the surface is more flat at the centerof the substantially optically transparent section and curves or slopesmore steeply away from the center of the substantially opticallytransparent section as shown by FIG. 18A-D. In some embodiments, themask has a size and the substantially optically transparent sections aredisposed such that the flatter central portions of the substantiallyoptically transparent section are along the line of sight of the wearer.Accordingly, in various embodiments, the surface is flatter closer tothe normal line of sight and slopes more steeply away from the normalline of sight.

Various embodiments of masks having optically transparent sections 224 aand 224 b that are curve and may be plano and have negligible opticalpower. Not having optical power will likely contribute to the comfortand viewing experience of the wear. Accordingly optically transparentsections 224 a and 224 b may have anterior and posterior surfaces havingshapes that together provide that the optically transparent sections 224a and 224 b have substantially zero diopters of optical power. In someembodiments, however, the optically transparent sections 224 a and 224 bmay have optical power such as to accommodate individuals who needrefractive correction.

In some embodiments, the angle of incidence varies across transparentsection 224. A curved window 224 depending on the shape and/or positionwith respect to the focus of the probe beam may cause the angle ofincidence to vary across the transparent section 224.

FIG. 19 schematically illustrates a window 224 of a mask disposed infront of a pair of eyes such that most of the rays of light from theincident beam are reflected at angles beyond the collection angle withinthe numerical aperture of the optics 270 or exceeds an offset angle Δdescribed above for beam-scanning devices. Accordingly, most of thelight does not re-enter the ophthalmic device. In particular, the window224 is sloped except for at the centerline where the nose of the weareris located. Additionally, the window has a slope that increases inmagnitude temporally. Moreover, the window is sloping such that all therays in the cone of rays 265 of the incident beam are directedtemporally upon reflection (unlike in the examples shown in FIGS.17A-C).

In the example shown in FIG. 19 , the window 224 has a slope andcurvature that increases in magnitude temporally such that the slope orcurvature is maximum at the periphery or edges 273 of the window 224.This slope or curvature at the location of the line of sight (e.g.,within a range of interpupilliary distances between 50-80 mm or 25-40 mmfrom the centerline) is sufficiently high in magnitude to exceed theangle of the ray 268 exiting the ophthalmic device (e.g., exiting theocular lens 270) at the largest angle that is incident onto the maskwindow 224. Additionally, the slope or curvature of the window 224 issufficently high in magnitude to deflect all or substantially all or atleast most of the other rays away from the optical axes 267 of theoutput channels of the ophthalmic device. At each point where rays fromthe probe beam intersect the window 224, the normal to the windowsurface is oriented with respect to the cone of rays 265 to deflect theray outwards or to retro-reflect the probe beam at an angle Δ describedpreviously for beam-scanning devices. Moreover, the rays are deflectedsufficiently so as not to be retro-reflected at an angle within thecollection angle defined by the numerical aperture of the output channelof the ophthalmic device such that this light is not coupled back intothe ophthalmic device so as to interfere with the signal (e.g., the OCTsignal).

Additionally, in various embodiments, the width of this curved window224 may be sufficient to account for the lateral position and movementof the oculars or output channels of the ophthalmic device. Increasingthe interpupillary distance of the pair of output channels of theophthalmic device effectively pushes the outermost ray 268 moretemporally. Accordingly, the width and curvature of the window 224 onthe mask can be established to ensure that half, or most, orsubstantially all, or all the rays of light from the left and rightoutput channels of the ophthalmic instrument are at a given instant intime or over the range of angles swept during a raster scan not incidenton the mask window at an angle where the rays are retro-reflected backat an angle within the collection angle defined by the numericalaperture of the channels such that the light is collected by thechannels and introduces noise to the signal. For example, if the angleof the ray 268 exiting the left and right channels of the ophthalmicdevice at the largest angle is 35 degrees (e.g., if the cone angle α is±35°), and the maximum lateral position of those rays is 40 mm from thecenterline 279 or nose line on the window of the mask, a shape can beconfigured for the window that ensures that none or substantially noneof the rays are incident on the transparent window in a perpendicularorientation and instead cause most, all, or substantially all theincident light to deflect outside the collection angle defined bynumerical aperture of the left and right channels of the ophthalmicdevices.

As discussed above, the substantially optically transparent sections 224a and 224 b have outer surfaces as seen from the front of the maskhaving a convex shape and are aspherical. For example, the curvedsurfaces may be ellipsoidal, toroidal, or have a shape characterized bya higher order polynomial or combinations thereof.

Additionally, in various embodiments the optically transparent sections224 a and 224 b are plano and have negligible optical power. Theoptically transparent sections 224 a and 224 b may have anterior andposterior surfaces having shapes that together provide that theoptically transparent sections 224 a and 224 b has substantially zerodiopters of optical power. In some embodiments, however, the opticallytransparent sections 224 a and 224 b may have optical power toaccommodate individuals who need refractive correction.

Moreover, the transparent section 224 can be comprised of a curvedtransparent outer surface sufficiently sloped such that the angle ofincidence of the rays of light output by an accompanying OCT machinewhen interfaced with the mask is not normal to the transparent section224 at most or substantially all the points of incidence on transparentsection 224 and the slope or tilt is configured to deflect the rays awayfrom the optical axis and outside the collection angle of the OCTmachine (e.g. |β|>α). In some embodiments, such as beam-steering opticaldevices, the difference between angle |β| and angle α is be greater thanan angle Δ such that |β|−Δ≥α to prevent any retro-reflected beam fromimpinging on the beam-steering device, such as a galvanometric mirror orMEMS mirror, and being sensed by the device. In some embodiments, thisrelationship is true for 50-60%, 60-70%, 70-80%, 80-90%, 90-95%, 95-98%,98-99%, or 99-100% of the light from the probe beam as used (e.g., floodillumination or swept) to generate images by the ophthalmic device orcombinations of these ranges.

Accordingly, in various embodiments, only 3-5% or 2-4%, or 1-3% or0.5-1% or 0.1-0.5% or 0.05-0.1% or 0.01-0.05% of the light is reflectedback into the ophthalmic device.

FIGS. 20A-D schematically illustrate a mask 300 for performing an eyeexam having transparent sections 224 with curvatures such as shown inFIG. 19 . Accordingly, the transparent sections 224, sometimes referredto herein as a mask window or curved transparent section, has wrap andsweeps back progressively with distance from a centerline of the mask(nasal line) 273 where the nose of the wearer would be positioned.Additionally, the mask window also has curvature in thesuperior-inferior meridian. Accordingly, this mask may reduceretro-reflection of light from the optical coherence tomographyinstrument back into the instrument.

In some embodiments, the curved transparent section 224 extends acrossall of distal portion 218. In some embodiments, curved transparentsection 224 is only a portion of distal portion 218 (e.g., see FIGS.21A-21D in which the optically transparent section does not extend to oris displaced from the lateral edges of the mask). As shown, the mask hasa front sheet that sweeps backward (e.g., posterior) and outward (e.g.,lateral) from the centerline 279 and provides suitable curvature toreduce reflection back into the OCT instrument and thereby reduce noiseon the OCT signal.

In certain embodiments for example, the mask includes left and rightsubstantially optically transparent sections 224 a, 224 b disposed onleft and right sides of the centerline 273. The left and rightsubstantially optically transparent sections 224 a, 224 b may bedisposed with respect to each other to accommodate interpupillarydistances (see FIG. 19 ) between about 50-80 mm, for example, foradults. Accordingly, the distance between the normal line of sight andthe centerline (which can be centered on the nose of the patent) isabout 25-40 mm. In some embodiments, at least the right substantiallyoptically transparent section 224 a (or the left section 224 b or both)has at least a portion thereof that is sloped such that at a location onthe right substantially optically transparent section 224 a (leftsection 224 b or both) that is 30 mm from the centerline (e.g., lateralof the superior inferior meridian), the right substantially opticallytransparent sections is sloped by at least 10° or more, at least 20° ormore, at least 30° or more, at least 40° or more, at least 50° or moreup to 70° or 80° or 90°, with respect to a line through that locationthat is parallel to the centerline. This angle may be established by thecone angle α discussed above and can have a magnitude greater than 10°such as more than 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, upto 70° or 80° or 90° etc. The right substantially optically transparentsection (or left section or both) may have the same slope magnitude orbe increasingly sloped (for example, have a magnitude greater than forexample 10° 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, or 60°) atlocations progressively more temporal from the location (e.g., greaterthan 30 mm in distance from the centerline) at least to about 35 mm or40 mm etc. from said centerline. In some embodiment, the location can be20 mm, 22.5 mm, 25, mm, 27 mm, 29 mm, 31 mm, 33 mm, 35 mm, 37 mm, or 39mm, or any range therebetween. In some embodiments, at 25 mm from thecenterline, the magnitude of the slope may be greater than for example10° 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, or 60° and/or the slopemay exceed the cone angle such that the outermost ray of light from theocular in the ophthalmic instrument is deflected away from the opticalaxis of the ocular. Likewise, for locations progressively more temporal,the optically transparent section may be sloped (for example, may have aslope with magnitude greater than for example 10° 15°, 20°, 25°, 30°,35°, 40°, 45°, 50°, 55°, 60°), may have constant slope, or varyingslope, e.g., increasingly sloped. Additionally, in some embodiments, theright (left or both) substantially optically transparent section(s) issloped by at least 15°, 17°, 19°, 21°, 23°, 25°, 27°, 29°, 31°, 33°,35°, 37°, 39°, 41°, 43°, 45°, 47°, 49°, 51°, 53° or 55°, in magnitude atsaid location or ranges therebetween. Accordingly, in some embodimentsthe substantially optically transparent section sweeps back asillustrated in FIG. 19 .

Likewise, the window exhibits wrap. In some embodiments, the windowwraps at least partially around the side of the face or at least beginsto wrap around the side of the face. This curvature is desirable wherethe rays of light from the ophthalmic instrument might intersect theoptically transparent window. Since different subjects will havedifferent interpupilary distances, and the ophthalmic instrument may beadjusted accordingly to direct the probe beam through the pupil of theeye, the rays from the probe beam may be incident over a range oflocations on the substantially optically transparent sections. A windowthat exhibits wrap over a region thereof may thus be desirable to reduceretro-reflection back into the instrument. In various embodiments,windows that sweep rearward with distance progressively more temporal ofthe centerline 273 of the mask 300 are useful in deflecting lighttemporally and outside the collection angle of the ophthalmic device.The slopes may be substantially constant in the temporal region or maybe varying.

Although FIG. 19 is a useful reference for the discussion above wherecurvature is shown along a nasal-temporal meridian, in considering thesuperior-inferior meridian, reference to FIGS. 17A-E may be beneficial.In various embodiments, the window is curved along the superior-inferiormeridian. This curvature as well as the distance of mask from the ocularon the ophthalmic instrument (as established by the mechanical interfacebetween the mask and the ophthalmic device) may be such that a pluralityof, many, possibly most, or substantially all rays in the bundle of raysfrom the ocular are deflected upward or downward and outside thecollection angle of the ocular.

In various embodiments, combinations of tilt directions and curvature oftransparent sections are possible. FIGS. 21-27 show additional designshaving differently shaped windows. FIGS. 21A-D as well FIGS. 26 and 27schematically illustrate a design having a planar portion 291 of thesubstantially transparent section that is located more nasally and anadjacent planar sloping portions 293 located temporally. A transition295 between these portions 291, 293 is curved. In certain embodiments,this transition 295 has a curvature of a circular arc having a centerand radius of curvature. The sloping portions may slope along anasal-temporal direction. Curvature or slope in the superior-inferiordirection is negligible. Additional discussion regarding this design isprovided below in connection with FIGS. 28A-D.

FIGS. 22-24 and 25A-D show transparent sections that are curved in bothnasal-temporal meridian and superior-inferior meridian. (FIGS. 22 and 23show the same compound curved surface as in FIG. 24 .) In variousembodiments such as shown in FIG. 25B, the curvature or slope of thesubstantially transparent section 301 in the nasal-temporal direction isnegligible closer to the centerline until reaching a temporal locationwhere the magnitude of the slope increases temporally to generate acurved temporal section that sweeps backward. The curvature or themagnitude of the slope of the substantially transparent section 301along the superior-inferior meridian starts out high in magnitude at theinferior location, reduces in magnitude to a negligible amount halfwaybetween the inferior and superior extent of the convex shapedsubstantially transparent section 301 and increases again at thesuperior locations. The curvature is such that the magnitude of slopeincreases with increasing distance superiorly and inferiorly beyond thecentral flat non-sloping region. The curvatures do not slope or theslope is substantially negligible along the nasal temporal meridian inthis central flat non-sloping region as well. In various embodimentsthis central flat non-sloping region can be ⅓ or ½ to ¾ the extent ofthe convex shaped substantially transparent section along the nasaltemporal meridian, the superior inferior meridian, or both.

FIGS. 28A-D illustrate some of the design considerations entailed invarious embodiments of the mask window. For certain ophthalmicinstruments, different modes of operation may involve use of probe beamswith different characteristics.

FIG. 28A for example, illustrates a mode of operation where an OCTinstrument is configured to output a planar non-focused wavefront.Optics in the OCT instrument are configured to be telecentric. FIG. 28Atherefore shows on a plot of angle of incidence (in degree) versusdistance (in mm) from the centerline, the output from the ocular oreyepieces for the left and right channels of the ophthalmic device(e.g., OCT instrument). The plot shows an angle of 0° for each of therays across the aperture of the ocular for both the left and rightchannels.

FIG. 28B illustrates a mode of operation where an OCT instrument isconfigured to output beam that sweeps across a range of angles α asdiscussed above. A plot of angle of incidence (in degree) versusdistance (in mm) from the centerline shows the output of the ocular oreyepieces for the left and right channels of the ophthalmic device(e.g., OCT instrument). These plots show the change in angle for thedifferent rays across the aperture of the ocular for both the left andright channels.

The OCT instrument is configured to provide modes of operation usingprobe beams characterized by the plots shown in FIGS. 28A and 28B.Accordingly, in various embodiments, a mask that can reduceretro-reflection back into the OCT system for both of these modes isbeneficial. The signal-to-noise ratio can thereby be increased bycurtailing introduction of noise into the signal by retro-reflection offthe mask. Accordingly, FIG. 28C shows the combination of angles ofincidence in the probe beam for the two modes on a single plot.

FIG. 28D presents a solution for reducing retro-reflection. As discussedabove, rays perpendicularly incident on the mask will be retro-reflectedback into the OCT instrument and introduce noise to the OCT signal.However, by adding a slight offset Δ to the reflected beam such that thebeam is not incident perpendicular on the mask and does not reflectdirectly back in the same direction the amount of rays that return backinto the OCT instrument can be reduced. The plot in FIG. 28D, shows theaddition of this offset. In particular, an offset of 1° has beenprovided.

In this example, the inter-optical distance, the distance between thecenters or optical axes of the oculars or eyepieces, which is related tothe interpupillary distance of the subject, was 54°. Accordingly, a lineof sight for wearers would be expected to be at 27° in both directionsfrom the centerline for each of the left and right eyes. The magnitudeof the slope of the mask is therefore set to increase continuously inthe regions between 27 mm and about 38 mm where the magnitude of theslope reaches a maximum (just beyond the angle of the outermost ray inthe bundle shown in FIGS. 28A and 28B). This curvature is to address themode of operation represented by FIG. 28B. The small 1° in the regionbetween 0 mm and 27 mm is to address the mode of operation representedby FIG. 28A where the rays are each at an angle of incidence of 0°without the offset. FIG. 28D shows a cross-section of the mask. Thecross-section shows a wide central region 291 between for the right eyebetween 0 and 27 mm without a large amount of slope, a transition region295 between 27 mm and 38 mm where the magnitude of the slope isincreasing, and a region 293 from 38 to 49 mm where the slope magnituderemains constant. A similar shape could be used for the left eye therebyproviding a symmetrical configuration.

Other variations are possible. For example, in one embodiment, for theright eye, the magnitude of the slope at 27 mm could be set to be solarge as to account for α+Δ, namely, β≥α+Δ at 27 mm. The transitionregion 295 could thus start around 13 or 14 mm and be complete by 27 mmwhere the magnitude of the slope could remain constant for distancesbeyond 27 mm (e.g., in region 293). In the region 291 between 0 to 13 or14 mm, the small slope offset of 1° or so could be introduced. A similarshape could be used for the left eye thereby providing a symmetricalconfiguration.

The various shaped windows may further include an AR coating asdiscussed above.

As illustrated in FIGS. 15B, 26, and 27 , rays of light corresponding tothe probe beam may be swept. For example, the probe beam (for OCT orSLO) may comprise a beam having a small beam width (e.g., 5 to 10 timesor more smaller than the exit pupil of the ocular) that is swept acrossthe focusing lens and/or exit pupil in the ocular of the ophthalmicdevice. Accordingly, only portions of the rays in the bundle of raysdescribed above will be present at a given time. Nevertheless, invarious embodiments, the beam sweeps through the different angles withinthe cone of angles, α, referred to above. Accordingly, as discussedabove, the shape of the mask window can be configured to be sufficientlysloped such that these rays, and in particular, this small beam, is notretro-reflected back into the instrument to introduce noise into thesignal as the beam is swept through the range of angles defined by thecone angle, α.

In some embodiments, similar to the mask 100 illustrated in FIG. 1 , theproximal portion 254 of the mask 200 is inflatable or deflatable, andthe rear surface 222 is configured to conform to contours of thepatient's face and align the one or more substantially opticallytransparent sections 224 of the distal portion 218 with the patient'seyes when the proximal portion 254 is inflated or deflated. In someembodiments, the mask 200 includes an inflation port (not shown)providing access to inflate or deflate the proximal portion 254. In someembodiments, the proximal portion 254 has two cavities 260 a and 260 bextending from the rear surface 222 toward the distal portion 218. Thetwo cavities 260 a and 260 b are aligned with the one or moresubstantially optically transparent sections 224 and defining twoopenings on the rear surface 222 to be aligned with the patient's eyes.The rear surface 222 is configured to seal against the patient's face soas to inhibit flow of fluid into and out of the two cavities 260 a and260 b through the rear surface 222. In some embodiments, the mask 200includes an ocular port (not shown) providing access to at least one ofthe two cavities for gas or fluid flow into the at least one of the twocavities 260 a and 260 b.

In some embodiments the mask is reusable. In other embodiments, the maskis single use or disposable and intended to be used by one patient,subject, or user, and subsequently disposed of and replaced with anothermask for use for another person.

In various embodiments, the optical transparent sections 124 of the maskare configured to increase or maximize transmission of light, such asfrom an OCT device, and the proximal portions 154 and concaved rearsurface 122 is configured to reduce or minimize transmission of light,such as ambient light or light not emanating from an OCT machine and maybe opaque and include opaque sides. For example, the proximal portions154 may have sides that are substantially non-transmissive to visiblewavelengths. These sides may for example block 80-90%, 90-95%, 95-99%,and/or 99-100% of ambient visible light. Reduction of ambient light mayfor example assist in keeping the patient's pupils dilated. Conversely,the optically transparent sections may have a transmittance of 70-80%,80-90%, 90-95%, 95-99%, and/or 99-99.5%, or 99.5%-100% or anycombination of these ranges in the wavelength range at which theophthalmic device operates such as at 450 nm, 515 nm, 532 nm, 630 nm,840 nm, 930 nm, 1060 nm, 1310 nm, or any combination thereof or acrossthe visible and/or near IR wavelength range or at least 10%, 20%, 30%,40%, 50%, 60%, 70%, 80%, or 90% of that range.

Other methods and configurations for reducing retro-reflection back intothe instrument can be used including any combination of the foregoingsuch as a combination of tilt and anti-reflective coatings.

Additionally, although various embodiments of the mask have beendiscussed above in connection with an optical coherence tomographydevice the mask may be used with other diagnostic instruments or devicesand in particular other ophthalmic devices such as a scanning laserophthalmoscope (SLO). One use for the AR coating on these goggles couldbe to increase transmission of emitted light into the eye. Opticalinstruments that sense back-reflected light (e.g. imaging instruments)often benefit from or require very sensitive instrumentation (e.g.avalanche photodiodes, interferometers, etc.) if the level ofback-reflected light is low. Additionally, since the tissues in the eyeare not very reflective, the low signal level of light back-reflectedfrom the eye tissue to be imaged or evaluated by the ophthalmic imagingor diagnostic systems may be lost in noise if the ghost back-reflectionsare sufficiently high. As discussed above, reducing the opticalinterfaces that will be perpendicular to the incident beam at any pointmay advantageously reduce back-reflection that introduced noise. Variousembodiments, therefore, employ tilting or curving the surface of thewindow. Additionally, signal can potentially be strengthened byincreasing transmission of light (and consequently by reducingreflections) at every surface to increase or maximize power going bothto and coming from the eye. This goal can be accomplished, for example,with AR coatings. Advantageously, in various embodiments, this increasedtransmission is accompanied by reduced reflections which improve thesignal-to-noise ratio (SNR) and contrast in the images or data producedand reduce ghost artifacts that can appear as real objects, for example,in an OCT or other image. Other instruments may benefit for similar ordifferent reasons.

As described herein, an ophthalmic diagnostic instrument such as anoptical coherence tomography device that may or may not employ ahygienic barrier, e.g., mask, such as described above may be used toassess the condition of a persons eyes. This diagnostic system mayobtain images of the structures of the eye using imaging technology suchas optical coherence tomography and also a scanning laserophthalmoscope. To assist with such imaging and/or provide additionaldiagnostics, the ophthalmic diagnostic instrument may additionallyinclude a system for tracking the position and/or orientation (e.g.,gaze direction) of the subject's eyes whose eyes and vision are beingevaluated.

OCT Eye Gaze Tracking

Eye tracking may be accomplished using optical coherence tomography(OCT) to detect the shape and/or location of the cornea and/or pupil ofthe eye. OCT typically utilizes low-coherence interferometry to generatetwo-dimensional and three-dimensional images of tissue at or near anouter surface. Thus, OCT may be used to image various tissues of theeye. For example, OCT may be used to obtain images of tissues such asthe cornea, iris, lens, anterior chamber (aqueous humor), retina, and/orother structures of the eye. An OCT device operates by directing anincident light beam onto a patient's eye and receiving a reflected orscattered light beam from the tissue. The incident light beam may beproduced from a light source such as one or more LEDs, flashlamps,superluminescent diodes, and/or lasers. The wavelengths present in theincident light beam may be selected based on the desired depth ofimaging, as different wavelengths may be capable of penetrating todifferent depths in eye tissues. The light source may be an incoherentsource or a source with low coherence. Collection of light from thelight source that is scattered by tissue in the eye may be used to imagethis tissue. By scanning the incident light beam in one or more lateraldirections, the OCT device may generate two-dimensional andthree-dimensional images (e.g., B-scans and/or C-scans) of desiredregions of the eye. The interferometer in the OCT device utilizes thecoherence properties to obtain high depth resolution. As will bedescribed in greater detail below, two-dimensional images depictingdimensions, shapes, and/or contours of the iris, pupil, and/or cornea ofan eye may be used to determine eye gaze direction. Determination of eyegaze direction may be accomplished by processing circuitry using methodsdescribed elsewhere herein.

FIGS. 29 a-29 c illustrate example methods of scanning an eye 2900 usingOCT to determine gaze direction. The method depicted in FIG. 29 a scansthe eye 2900 using a vertical scan path 2904 in a vertical lateraldirection and a horizontal scan path 2905 in a horizontal lateraldirection. Each scan path allows the scanning OCT device to image atleast a portion of the iris 2902 of the eye 2900 and the pupil 2901defined by the pupillary border 2903 at the interior edge of the iris2902. The cornea (not shown) is anterior to the iris 2902 and pupil2901, and may be imaged as well. The vertical scan path 2904 and thehorizontal scan path 2905 may extend laterally beyond the edge of theiris 2902, may extend laterally beyond the edge of the cornea or becontained entirely within the en face boundaries of the cornea or iris2902. A horizontal and vertical scanning pattern may be advantageousbecause each scan path provides an equal amount of information about themovement of the eye gaze location in the horizontal and verticaldirections.

The method depicted in FIG. 29 b scans an eye 2900 using an “x pattern”including slanted scan paths 2906 and 2907. The compressed aspect ratioachieved by using scan paths angled less than 45° from the horizontallateral direction may be more consistent with the typical shape of aneyelid opening, and thus may allow a greater portion of the iris 2902and pupil 2901 to be imaged by avoiding obstruction by the eyelids.However, the data received from an “x pattern” scan may be moredifficult to use because the two scan paths 2906 and 2907 are not normalto each other, and may provide less information about the gaze positionin the vertical lateral direction.

The method depicted in FIG. 29 c scans an eye 2900 using an “infinitypattern” including a single continuous path 2908. The single continuouspath 2908 may be faster to acquire than the two discrete paths of thescan patterns depicted in FIGS. 29 a and 29 b since it does not requireabrupt accelerations and decelerations of the beam scanning apparatus.Instead, the consistently sloping curvature of scan path 2908 reducesacceleration and deceleration forces on the beam scanning assembly suchthat the speed of beam scanning can be greater than scan patterns thatrequire abrupt changes in beam direction. Like the pattern of FIG. 29 b, the “infinity pattern” may be limited in its ability to accuratelydetect the vertical component of an eye gaze location. However, any ofthe methods depicted in FIGS. 29 a-29 c , as well as any other scanningmethod, may be used in determining an eye gaze location, as described ingreater detail below.

FIG. 30 a is a cross sectional view of an eye 2900 taken at a horizontalplane depicting the eye 2900 looking straight ahead. FIG. 30 b depictsthe same eye 2900 looking to the left due to rotation about the eye'saxis of rotation 2912. Similarly, FIG. 30 c depicts the eye 2900 lookingto the right due to rotation about the eye's axis of rotation 2912. FIG.30 d depicts a front view of a pupil 2901 of the forward-looking eye2900 depicted in FIG. 30 a . FIG. 30 e depicts a front view of a pupil2901 of the left-looking eye 2900 depicted in FIG. 30 b . FIG. 30 fdepicts a front view of a pupil 2901 of the right-looking eye 2900depicted in FIG. 30 c . As described above, the pupil 2901 is defined bya pupillary border 2903 at the inner edge of the iris 2902. The shape ofthe pupil is visible through the cornea 2910, which is typically clearor substantially clear.

In some embodiments, eye gaze location may be tracked based on the shapeand/or aspect ratio of the pupil 2901. When the eye 2900 of a normalsubject is looking straight ahead as depicted in FIG. 30 a , the pupil2901 appears round to a viewer directly in front of the subject becausethe viewer is looking at the eye in the longitudinal direction, alongthe eye's axis of symmetry. When the eye 2900 rotates to look to theleft as depicted in FIG. 30 b , the pupil appears to flatten orforeshorten into an elliptical shape as depicted in FIG. 30 e .Similarly, when the eye rotates to look to the right as depicted in FIG.30 c , the pupil appears to tilt, flatten, or foreshorten into anelliptical shape as depicted in FIG. 30 f . Thus, in some embodiments,eye gaze direction may be detected and/or tracked based on the aspectratio of the pupil. When the eye of a subject with an abnormal pupil islooking straight ahead, the pupil may not appear to be round but itshorizontal and vertical dimensions may still be greatest in straightahead gaze. Tilting, foreshortening or flattening as discussed abovewill still occur in eccentric gaze in proportion to the gaze angle forthe abnormal pupil. Gaze angle calculation based on ellipticity of thepupil will be discussed in greater detail with reference to FIGS. 3 a -3f.

FIGS. 31 a-31 c depict horizontal 2-dimensional OCT scans of the eyesdepicted in FIGS. 30 a-30 c . FIG. 31 a depicts the forward-looking eyedepicted in FIG. 30 a , FIG. 31 b depicts the left-looking eye depictedin FIG. 30 b , and FIG. 31 c depicts the right-looking eye depicted inFIG. 30 c . FIGS. 31 d-31 f depict vertical 2-dimensional OCT scans ofthe eyes depicted in FIGS. 30 a-30 c and 31 a-31 c . The scan of FIG. 31d corresponds to the forward-looking eye depicted in FIG. 31 a , whilethe scan of FIG. 31 e corresponds to the left-looking eye depicted inFIG. 31 b , and the scan of FIG. 31 f corresponds to the right-lookingeye depicted in FIG. 31 c.

The scans in FIGS. 31 a-31 f are 2-dimensional cross-section scans, orB-scans, made up of a series of 1-dimensional A-scans. An A-scan showsthe scatter of light along different distances in the longitudinaldirection. Likewise, data from an A-scan indicates the distance to eachoptical interface along a single line in the longitudinal direction. Aseries of longitudinal 1-dimensional A-scans taken at different pointsalong a line across the eye can produce a 2-dimensional B-scan. Forexample, the B-scans depicted in FIGS. 31 a-31 c are produced from aseries of A-scans taken at points along a horizontal lateral path, whilethe B-scans depicted in FIGS. 31 d-31 f are produced from a series ofA-scans taken at different points along a vertical lateral path.

As described above, the width of a pupil 2901 may be seen to decreasewhen the eye looks to the left or right. For example, in the scans ofFIGS. 31 a-31 c , the width of the pupil 2901 as measured between theedges 2903 of the iris 2902 may have a width, for example, ofapproximately 4 mm in the horizontal lateral direction when the eye islooking straight ahead. When the eye looks to the left or right asdepicted in FIGS. 31 b and 31 c , the width of the pupil 2901 in thehorizontal lateral direction (i.e., as viewed along a longitudinal axis)decreases, for example, to approximately 3 mm due to the tilting of thepupil relative to the longitudinal axis. However, the vertical scans ofFIGS. 31 d-31 f show that the height of the pupil 2901 in the verticallateral direction remains substantially constant at, for example,approximately 4 mm. Thus, the aspect ratio of the pupil of aforward-looking eye is different from the aspect ratio of the pupil of aleft-looking or right-looking eye. A similar effect may be observed forrotation of the eye in a vertical direction. For vertical movement of aneye's gaze location, the width of the pupil in the horizontal lateraldirection may remain constant, while the height of the pupil in thevertical lateral direction may decrease. Although the aspect ratio ofthe pupil may detect a shift in eye gaze location, it may be difficultto determine which direction the eye moved because a rotation of the eyeto the left will result in the same change in pupillary aspect ratio asa similar rotation of the eye to the right.

An alternative method of tracking eye gaze location based on themovement of a pupillary border may provide greater accuracy. FIGS. 32a-32 c illustrate an example method of determining an eye gaze anglebased on lateral movement of a pupillary border 2903. As described abovewith reference to FIGS. 31 a -31 f, 2-dimensional OCT scans may be usedto image the iris 2902, including the inner edge of the iris 2902 at thepupillary border 2903. A longitudinal meridian 2920 may extend from theaxis of rotation 2912 of the eye 2900 along a longitudinal direction.Thus, when the eye 2900 is looking straight ahead, as depicted in FIG.32 a , the longitudinal meridian 2920 may extend through or near thecenter of the pupil 2901. A lateral distance 2922 between the pupillaryborder 2903 and the longitudinal meridian 2920 may be measured using OCTscanning, similar to the method described above with reference to FIGS.31 a -31 c.

The eye 2900 depicted in FIG. 32 b has rotated and is looking to theleft. Accordingly, the lateral distance 2922 between the pupillaryborder 2903 and the longitudinal meridian in FIG. 32 b is greater thanthe lateral distance 2922 in FIG. 32 a . The increased lateral distance2922 may be detected by an OCT system as an indication that the eye gazelocation has shifted to the left. Moreover, the change in the lateraldistance 2922 may be proportional to the change in eye gaze location,allowing the OCT system to accurately track the change in eye gazelocation. Similarly, a rotation of the eye 2900 to the right, as shownin FIG. 32 c , may be detected as a decrease in the lateral distance2922. In FIG. 32 c , the eye has rotated rightward until the lateraldistance decreased to zero. In some embodiments, an OCT system may beable to detect a zero or negative lateral distance 2922 if the pupillaryborder 2903 moves to or beyond the longitudinal meridian 2920. In otherembodiments, an OCT system may use both pupillary borders on either sideof a longitudinal meridian to detect and measure eye gaze location.Thus, eye gaze location may be tracked based on determining the lateraldistance 2922 between a pupillary border 2903 and a longitudinalmeridian 2920. In some embodiments, 3-dimensional eye gaze tracking maybe accomplished by simultaneously or consecutively scanning the eye 2900along two different lateral axes. For example, the eye 2900 may bescanned along a horizontal lateral axis to measure a horizontalcomponent of the eye gaze angle and/or location, and along a verticallateral axis to measure a vertical component of the eye gaze angleand/or location. However, eye gaze tracking based on the location of apupillary border 2903 may be complicated by pupil dilation orcontraction due to changing light conditions, decentration of thehorizontal or vertical scan paths in relation to the pupil center, or byany of various pathologies of the iris which may affect the shape and/orfunction of the iris.

In any of the eye gaze tracking methods based on the location of one ormore points along a pupillary border 2903, a tilt of the plane of thepupil 2901 may be calculated based on any observed foreshortening and/orflattening. Moreover, a function such as a circle or plane may be fittedto match the shape and/or plane of the pupil. In some embodiments, oneor more gaze vectors passing through and normal to the fitted circle orplane may be calculated. For example, a gaze vector may pass through andbe normal to the center of a circle fitted to the shape of a pupillaryborder of an eye. In some embodiments, two B-scans may be taken, eachextending through the pupil and two pupillary borders, resulting in thedetection of up to 4 four points along the iris-pupil boundary. Thecombined information can be utilized to calculate a vector correspondingto the gaze, such as a normal vector approximating the gaze direction.If three points along the iris-pupil boundary are detected, a circle maybe fitted to those three points. If four points along the iris-pupilboundary are detected, iterative methods as described elsewhere herein,such as RANSAC, may be used to fit a circle. As described above, sincethree points can be used to definitively describe a circle or plane,various three point combinations of the four pupillary border points maybe used independently to derive the function to fit each set of threepoints. The consensus function that best fits all of these functions,such as by minimizing maximum error, can then be determined. In someembodiments, the consensus function is derived using Random SampleConsensus (RANSAC). In some embodiments, noise or outlier rejectionalgorithms may be used to eliminate one of the four points to enablecalculation of a function from the remaining three points.

Other methods are possible. For example, in some methods, multipleB-scans are obtained through the iris-pupil boundary. Lines through theintersections of the B-scans with the iris-pupil boundary each defineplanes normal to the line at the midpoint along the line betweenintersections. These planes may intersect along a line which enablescalculation of a vector approximating the gaze. In particular, in someembodiments, for example, the intersection of these two planes defines avector that approximates the gaze direction.

FIGS. 32 d-i illustrate an example method of detecting pupillary borderpoints using OCT B-scans. An eye 2900 includes a cornea 2910, an iris2902, and a pupil 2901, bounded by a pupillary border 2903, as depictedin FIG. 32 d-e . FIGS. 32 f-g show example paths and planes of two OCTB-scans across the eye depicted in FIGS. 32 d-e . As described elsewhereherein, OCT B-scans include a plurality of A-scans, and may imagemultiple structures at different depths within the eye 2900, such as thecornea 2910 and the iris 2902, in 2 dimensions. FIGS. 32 h-i depict thesame OCT scan paths depicted in FIGS. 32 f-g , with the scanning planesshifted longitudinally to show where pupillary border points 2954 may bedetected based on the B-scans 2950 and 2952.

FIGS. 32 j-k depict example arrangements of OCT B-scan paths 2950 and2952. The arrangement of FIG. 32 j includes two perpendicular scan paths2950 and 2952 (i.e., at an angle of 90° with respect to each other),while the arrangement of FIG. 32 k includes two parallel scan paths 2950and 2952 (i.e., at an angle of 0° with respect to each other). Invarious embodiments, the second scan path 2952 may be oriented at anyangle between 0° and 90° relative to the first scan path 2950. If theparallel scan paths 2950 and 2952 depicted in FIG. 32 k are spacedlaterally such that they intersect the pupillary border 2903 atdifferent points, three or more pupillary border points may still beobtained in total, allowing a circle to be fit to the points asdescribed elsewhere herein.

FIGS. 32 l-m depict an example process of modeling the shape andorientation of the pupil 2901 by fitting a circle 2956 based on detectedpupillary border points 2954. A circle may be uniquely defined by threepoints. Thus, if three or four pupillary border points 2954 are detectedbased on two OCT B-scans, a circle 2956 passing through the points maybe calculated, allowing the orientation of the pupil to be determined.If four points 2954 are detected, the equation of the fitted circle 2956may be over-constrained, and a best fit circle may be derived by any ofthe iterative methods described herein, such as RANSAC. Other techniquesto obtain the circle or other function may be employed if four pointsare obtained.

FIGS. 32 n-o schematically illustrate an example longitudinal meridian,as described elsewhere herein. In an eye looking straight ahead asdepicted in FIG. 32 n , a longitudinal meridian may coincide with or beparallel to a normal vector to the midpoint of the pupil of an eye. Thenormal vector at the midpoint of the pupil may further extend throughthe corneal apex. When the eye is rotated to look to the side asdepicted in FIG. 32 o , the longitudinal meridian may be retained alongthe original direction of FIG. 32 n , while the normal vector at themidpoint of the pupil of FIG. 32 o has shifted due to the tilt of thepupil associated with the rotation of the eye.

FIGS. 32 p-s depict an example method of detecting an eye gaze directionvector based on two OCT B-scans. After a circle is fitted to the threeor four pupillary border points detected by two OCT B-scans as describedabove, a midpoint 2958 of the pupil may then be calculated from theequation of the circle.

FIGS. 32 t-w depict another example method of detecting an eye gazedirection vector based on two OCT B-scans. As described above, in someembodiments, two B-scans 2973 and 2975 may each detect two pupillaryborder points. For each B-scan 2973 and 2975, a midpoint may becalculated between the two border points. In some cases, the midpointsof the B-scans may not be the same as the midpoint of the pupil. Thus,one or both of the midpoints may be points other than the midpoint ofthe pupil. A first normal vector 2970 at a midpoint in the first B-scan2973 may be calculated, and a second normal vector 2972 at a midpoint inthe second B-scan 2975 may be calculated. A first vector 2970 may becalculated as a vector within the plane of the first OCT B-scan 2973,normal to the line formed by the points on that line intersecting at theiris-pupil boundary. The vector 2970 can be located at the midpointbetween the two points on that line intersecting the iris-pupilboundary. A second vector 2972 may be calculated similarly as a vectorwithin the plane of the second OCT B-scan 2975, normal to the lineformed by the points on that line intersecting at iris-pupil boundary.The second vector 2972 can be also located at the midpoint between thetwo points on that line intersecting at the iris-pupil boundary. Tolocate the center of the pupil, the first normal vector 2970 may betranslated laterally so as to lie within the plane orthogonal to thesecond B-scan 2975 located at the midpoint between the iris-pupilboundary points determined by the second B-scan 2975. Alternatively, thesecond normal vector 2972 may be translated laterally so as to liewithin the plane orthogonal to the first B-scan 2973 located at themidpoint between the iris-pupil boundary points intersecting the firstB-scan 2973. The normal vectors 2970 and 2972 may then be combined bythree-dimensional vector addition to produce a final direction vector2974 approximating the gaze direction of the eye.

The table below summarizes the applicability of the various pupil-basedeye gaze tracking methods described above.

4 point OCT Scan 1 OCT Scan 2 Gaze from distance Gaze from normal vector3 point iterative Pupil Pupil Pupil Pupil between pupil border to linebetween pupil circle/ circle/ Borders Midpoints Borders Midpoints andlong. meridian borders (midpoint) plane fit plane fit 1 0 0 0 1dimension — — — 1 0 1 0 2 dimensions — — — 1 0 2 1 2 dimensions 1dimension Yes — 2 1 2 1 2 dimensions 2 dimensions (4 point) Yes

As described above with reference to FIGS. 29 a-29 c , the location andlength of a scan path and/or the position of an eyelid may prevent asingle linear scan from detecting two pupillary borders. As shown in thetable, a pupillary midpoint can be calculated if two pupillary bordersare detected in a single linear OCT B-scan. However, the methodsdescribed above may still be used to track the gaze of an eye in theevent that two complete B-scans, each detecting two pupillary borderpoints, are not obtained. For example, a single B-scan detecting only asingle pupillary border point may be used to determine an eye gazelocation in one dimension based on the distance between the pupillaryborder point and a longitudinal meridian, as described elsewhere herein.If two B-scans are obtained, each detecting only a single pupillaryborder point, the longitudinal meridian-based method may be used todetermine an eye gaze location in two dimensions. If one of the twoB-scans detects two pupillary border points, it may also be possible todetermine an eye gaze based on either or both of a normal vectorcalculated at the midpoint between the pupillary borders, and based on a3-point circle/plane fitted to the three detected pupillary borderpoints. If both B-scans detect two pupillary border points, it mayadditionally be possible to improve the accuracy of the determined gazelocation by iteratively fitting a circle and/or plane to the fourdetected pupillary border points, as described elsewhere herein.

Alternatively, eye gaze location may be tracked based on the location ofthe corneal apex. FIGS. 33 a-33 c illustrate an example method ofdetermining an eye gaze angle based on lateral movement of the cornealapex 2932. Measuring eye gaze angle based on movement of the cornealapex 2932 may be desirable because the cornea 2910 tends to maintain aregular shape, even in the case of various corneal pathologies. Theouter surface of a cornea 2910 is typically a circular paraboloid,elliptical paraboloid, or similar shape, having an apex 2932 on or nearthe visual axis. Any lateral displacement between the corneal apex 2932and the point where the visual axis crosses the corneal surface isgenerally fixed. Thus, any lateral movement of the corneal apex 2932 maycorrespond to an equivalent movement of the point of gaze of the eye,and the gaze location may be tracked by tracking the location of thecorneal apex 2932. In some embodiments, the gaze location and/or anglemay be calculated from the location of the corneal apex 2932 bycalculating a gaze vector, which may pass through and be normal to thecorneal apex location.

The location and movement of the corneal apex 2932 along any axis (e.g.,horizontal, vertical, or a combination of both longitudinal axes) may betracked by fitting a parabola 2930 to the shape of the outer surface ofthe cornea 2910. A parabola 2930 corresponding to the shape of the outersurface of the cornea 2910 may be calculated based on longitudinaldistance information obtained from one or more OCT A-scans. Because theouter surface of the cornea is generally the most anterior surface ofthe eye, the shortest distance for which a reflectivity peak is detectedin an A-scan may correspond to the distance to the outer surface of thecornea. This distance measurement may be a longitudinal z coordinate.The longitudinal z coordinate may be combined with a two-dimensionallateral location of the A-scan (e.g., x and y in a lateral plane) toproduce a three-dimensionally defined point (e.g., (x, y, z) in aCartesian coordinate system). Calculation of a parabola based onlongitudinal distance information is discussed below with reference toFIGS. 34 a-34 d . The location of the apex 2932 of the parabola may thenbe calculated from the calculated parabolic function.

Rotation of the eye 2900 may be determined based on movement of thecorneal apex 2932. In some embodiments, an OCT system may be configuredto repeatedly scan the cornea 2910 and calculate a corneal surfaceparabola 2930 and corresponding apex 2932. For example, the system maybe configured to scan the cornea 2910 and determine an apex 2932location at a regular interval, such as every 10 milliseconds, 50milliseconds, 100 milliseconds, or at intervals within ranges defined bythese values, or at any other suitable scanning interval. After eachscan, the system may calculate a lateral shift 2936 from a previous apexlocation 2932 to a new apex location 2934. In some embodiments, theprevious apex location 2932 may correspond to an eye 2900 lookingstraight ahead, an original reference location, or the location of theapex 2932 from any previous scan.

For example, FIG. 33 a depicts an eye 2900 looking straight ahead. Aparabola 2930 may be calculated based on the outer surface of the cornea2910, and the apex 2932 may be calculated from the equation of theparabola. FIG. 33 b depicts an eye 2900 that has rotated to look to theleft. After the rotation to the left, the cornea 2910 may be scannedagain and a new parabola 2930 can be calculated to model the outersurface of the cornea 2910. A new apex 2934 can be determined based onthe new parabola 2930, and the lateral shift between the original apex2932 and the new apex 2934 may be calculated. The same process may beapplied to the right-looking eye 2900 depicted in FIG. 33 c . Moreover,if the distance 2933 between the conical apex 2934 and the center ofrotation 2931 of the eye 2900 is known, the change in gaze angle φ 2935may be calculated as well. The change in gaze angle φ 2935 may becalculated using the equation tan(φ)=x/z, where x is the lateral shift2936 and z is the distance 2933 between the conical apex 2934 and thecenter of rotation 2931 of the eye 2900 in reference to the conicalsurface such as 13.5 mm, 13 mm, 14 mm, or other measurements in therange of the length of an eye such as between 18 mm and 40 mm.

In some embodiments, similar methods may be used to track eye gazelocation in three dimensions. FIGS. 34 a-34 d illustrate an examplemethod of calculating a 3-dimensional function or surface 2940representing the shape of a cornea based on multiple 2-dimensionalfunctions or curves. FIG. 34 a depicts an example function or surface2940, which may be a circular paraboloid, elliptical paraboloid, orsimilar 3-dimensional function or surface. A paraboloid 2940 may offer aclose approximation or exact fit of the actual shape of a human cornea.The paraboloid 2940 may have a single apex 2942 at a locationcorresponding to the location of the corneal apex of the cornea beingmodeled or approximated. Moreover, the location of the apex 2942 of theparaboloid 2940 may be calculated easily once an equation of theparaboloid 2940 has been determined. Other surfaces, including othersymmetric surfaces such as other rotationally symmetric surfaces may beutilized. Still other surfaces that are not rotationally symmetric orthat are not symmetric may be used as well.

To determine an equation of the paraboloid 2940, two 2-dimensionalparabolas 2944 and 2946, or cross sections, of the paraboloid 2940 mayfirst be determined. In some embodiments, parabola 2944 may be normal toparabola 2946, or the parabolas 2944 and 2946 may intersect at any otherangle. In some embodiments, parabolas 2944 and 2946 may not intersect.Moreover, parabolas 2944 and 2946 need not include the apex 2942.

FIGS. 34 c and 34 d depict an example process of determining parabolas2944 and 2946, both of which may be located along the surface of theparaboloid 2940. Each parabola 2944, 2946 may be calculated based on aset of points 2945, 2947 obtained from an OCT B-scan of the cornea, orany other suitable method of determining longitudinal distanceinformation for a point on the outer surface of a cornea. In someembodiments, a set of points 2945, 2947 may include at least threepoints so as to define a parabola. If only three points are used, themethod may be limited to calculating a parabola with a vertical axis ofsymmetry assumed. If four or more points are used, it may be possible tocalculate a non-vertical axis of symmetry of the parabola as well, so asto more accurately approximate the shape and tilt of the conicalsurface. Processing circuitry may generate an equation of parabola 2944by determining a parabolic function that passes through all three orfour points of set 2945. Similarly, processing circuitry may generate anequation of parabola 2946 by determining a parabolic function thatpasses through all three or four points of set 2947. In someembodiments, more than four points may be used. However, the parabolicfunctions may then be overdetermined, and approximation and/or iterativesolving methods, such as Random Sample Consensus (RANSAC), may beuseful. In other embodiments, multiple parabola equations may begenerated from multiple sets of three or four points from the samecorneal OCT scan. Processing circuitry may select the parabolarepresenting the best consensus fit out of the group or calculate anaverage or otherwise de novo parabolic function based on somecombination of these multiple parabolas.

After determining equations of parabolas 2944 and 2946, the processingcircuitry may then determine an equation of a 3-dimensional paraboloid2940 that includes both of parabolas 2944 and 2946. If parabolas 2944and 2946 were determined based on sets 2945, 2947 containing threepoints each, there may be a unique circular paraboloid containing bothparabolas 2944 and 2946. If parabolas 2944 and 2946 were determinedbased on sets 2945, 2947 containing four points each, the paraboloidfunction may be overdetermined. If the paraboloid is overdetermined, anapproximate solution may be found. For example, processing circuitry maycompute an approximate paraboloid function based on any suitable leastsquares approximation method, regression analysis, iterativeapproximation method such as RANSAC, or other suitable method fordetermining an equation of a paraboloid that approximates a paraboloid2940 defined by parabolas 2944 and 2946. From the determined paraboloidequation, the location of the apex of the paraboloid 2940 may becalculated. The eye gaze angle in three dimensions may be calculated asdescribed above with reference to 2-dimensional eye gaze anglecalculation in FIG. 33 c.

FIG. 35 illustrates an example method of directly calculating a circularor elliptical paraboloid 2940 representing the shape of a cornea. Insome embodiments, an OCT system may calculate a 3-dimensional shape ofthe cornea directly from a plurality of points 2948 without anintermediate step of calculating 2-dimensional functions. For example,the surface may be a paraboloid 2940. As described elsewhere, a uniqueparaboloid 2940 may be defined by six points 2948. In some embodiments,the OCT system may be configured to acquire longitudinal depthinformation at a set of six or more points 2948 of the outer surface ofthe cornea of an eye. Processing circuitry may be configured tocalculate a paraboloid 2940 defined by the set of points 2948. For a setof six points 2948, the circuitry may calculate the unique paraboloid2940 defined by the set. For sets of more than six points 2948, theparaboloid 2940 function may be overdetermined, and the processingcircuitry may calculate a best fit, as described elsewhere herein. Inother embodiments, the processing circuitry may calculate paraboloidfunctions for some, many, or all subsets of six points and then pick theparaboloid that represents the best consensus in the group or calculatea new paraboloid based on a least squares approximation, regressionanalysis, or other suitable method. When a 3-dimensional function 2940corresponding to the set of points 2948 has been calculated, thelocation of the apex 2942 of the function may be determined. Thelocation and/or movement of the apex 2942 may be used to track eye gazelocation using any of the methods described herein as well as othermethods.

While the invention has been discussed in terms of certain embodiments,it should be appreciated that the invention is not so limited. Theembodiments are explained herein by way of example, and there arenumerous modifications, variations and other embodiments that may beemployed that would still be within the scope of the present disclosure.

For purposes of this disclosure, certain aspects, advantages, and novelfeatures of the invention are described herein. It is to be understoodthat not necessarily all such advantages may be achieved in accordancewith any particular embodiment of the invention. Thus, for example,those skilled in the art will recognize that the invention may beembodied or carried out in a manner that achieves one advantage or groupof advantages as taught herein without necessarily achieving otheradvantages as may be taught or suggested herein.

It will be appreciated that each of the processes and methods describedherein and/or depicted in the figures may be embodied in, and fully orpartially automated by, code modules executed by one or more physicalcomputing systems, processing circuitry, hardware computer processors,application-specific circuitry, and/or electronic hardware configured toexecute specific and particular computer instructions. For example,computing systems can include general purpose computers (e.g., servers)programmed with specific computer instructions or special purposecomputers, special purpose circuitry, and so forth. A code module may becompiled and linked into an executable program, installed in a dynamiclink library, or may be written in an interpreted programming language.In some embodiments, particular operations and methods may be performedby circuitry that is specific to a given function.

Indeed, it will be appreciated that the systems and methods of thedisclosure each have several innovative aspects, no single one of whichis solely responsible or required for the desirable attributes disclosedherein. The various features and processes described above may be usedindependently of one another, or may be combined in various ways. Allpossible combinations and subcombinations are intended to fall withinthe scope of this disclosure.

Certain features that are described in this specification in the contextof separate embodiments also can be implemented in combination in asingle embodiment. Conversely, various features that are described inthe context of a single embodiment also can be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination. No single feature orgroup of features is necessary or indispensable to each and everyembodiment.

It will be appreciated that conditional language used herein, such as,among others, “can,” “could,” “might,” “may,” “e.g.,” and the like,unless specifically stated otherwise, or otherwise understood within thecontext as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements and/or steps. Thus, such conditional language is notgenerally intended to imply that features, elements and/or steps are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or withoutauthor input or prompting, whether these features, elements and/or stepsare included or are to be performed in any particular embodiment. Theterms “comprising,” “including,” “having,” and the like are synonymousand are used inclusively, in an open-ended fashion, and do not excludeadditional elements, features, acts, operations, and so forth. Also, theterm “or” is used in its inclusive sense (and not in its exclusivesense) so that when used, for example, to connect a list of elements,the term “or” means one, some, or all of the elements in the list. Inaddition, the articles “a,” “an,” and “the” as used in this applicationand the appended claims are to be construed to mean “one or more” or “atleast one” unless specified otherwise. Similarly, while operations maybe depicted in the drawings in a particular order, it is to berecognized that such operations need not be performed in the particularorder shown or in sequential order, or that all illustrated operationsbe performed, to achieve desirable results. Further, the drawings mayschematically depict one more example processes in the form of aflowchart. However, other operations that are not depicted can beincorporated in the example methods and processes that are schematicallyillustrated. For example, one or more additional operations can beperformed before, after, simultaneously, or between any of theillustrated operations. Additionally, the operations may be rearrangedor reordered in other embodiments. In certain circumstances,multitasking and parallel processing may be advantageous. Moreover, theseparation of various system components in the embodiments describedabove should not be understood as requiring such separation in allembodiments, and it should be understood that the described programcomponents and systems can generally be integrated together in a singlesoftware product or packaged into multiple software products.Additionally, other embodiments are within the scope of the followingclaims. In some cases, the actions recited in the claims can beperformed in a different order and still achieve desirable results.

Accordingly, the claims are not intended to be limited to theembodiments shown herein, but are to be accorded the widest scopeconsistent with this disclosure, the principles and the novel featuresdisclosed herein.

While the invention has been discussed in terms of certain embodiments,it should be appreciated that the invention is not so limited. Theembodiments are explained herein by way of example, and there arenumerous modifications, variations and other embodiments that may beemployed that would still be within the scope of the present invention.

For purposes of this disclosure, certain aspects, advantages, and novelfeatures of the invention are described herein. It is to be understoodthat not necessarily all such advantages may be achieved in accordancewith any particular embodiment of the invention. Thus, for example,those skilled in the art will recognize that the invention may beembodied or carried out in a manner that achieves one advantage or groupof advantages as taught herein without necessarily achieving otheradvantages as may be taught or suggested herein.

As used herein, the relative terms “temporal” and “nasal” shall bedefined from the perspective of the person wearing the mask. Thus,temporal refers to the direction of the temples and nasal refers to thedirection of the nose.

As used herein, the relative terms “superior” and “inferior” shall bedefined from the perspective of the person wearing the mask. Thus,superior refers to the direction of the vertex of the head and inferiorrefers to the direction of the feet.

EXAMPLES

The following example embodiments identify some possible permutations ofcombinations of features disclosed herein, although other permutationsof combinations of features are also possible.

1. A method of detecting an eye gaze direction, the method comprising:

-   -   performing at least one OCT scan of an outer surface of the eye;    -   determining an orientation of the cornea of the eye based on the        at least one OCT scan of the cornea; and    -   calculating an eye gaze direction based at least in part on the        orientation of the cornea.

2. The method of Example 1, wherein the at least one OCT scan comprisesat least three longitudinal A-scans spaced linearly along a lateraldirection.

3. The method of Example 1, wherein the at least one OCT scan comprisesat least four longitudinal A-scans spaced linearly along a lateraldirection.

4. The method of any one of the preceding Examples, wherein determiningthe orientation of the cornea comprises:

-   -   determining a longitudinal coordinate of the outer surface of        the cornea for at least three longitudinal A-scans; and    -   fitting a two-dimensional parabolic function to the determined        longitudinal coordinates.

5. The method of any one of the preceding Examples, further comprisingdetermining a location of a corneal apex of the eye.

6. The method of Example 5, wherein determining a location of a cornealapex further comprises calculating the location of the apex of thetwo-dimensional parabolic function.

7. The method of Example 5 or 6, further comprising calculating a gazevector normal to the cornea at the corneal apex.

8. The method of any one of the preceding Examples, further comprisingdetermining an axis of symmetry of the eye.

9. The method of Example 1, wherein the method comprises performing atleast two OCT scans of an outer surface of the eye, and wherein theorientation of the cornea is determined based on the at least two OCTscans.

10. The method of Example 9, wherein determining the orientation of thecornea further comprises calculating a three-dimensional function basedon the two-dimensional parabolic functions of the at least two OCTscans.

11. The method of Example 10, wherein determining the orientation of thecornea comprises determining the location of a corneal apex bycalculating the location of an apex of the three-dimensional function.

12. The method of Example 11, further comprising calculating a gazevector normal to the cornea at the corneal apex.

13. The method of Example 10, further comprising determining an axis ofsymmetry of the eye.

14. The method of any one of Examples 10 to 13, wherein thethree-dimensional function comprises a paraboloid.

15. The method of any one of Examples 10 to 13, wherein thethree-dimensional function comprises a symmetric function.

16. The method of any one of Examples 10 to 13, wherein thethree-dimensional function comprises a rotationally symmetric function.

17. The method of Example 1, wherein the at least one OCT scan comprisesat least six laterally spaced longitudinal A-scans.

18. The method of Example 17, wherein determining a shape of the corneacomprises:

-   -   determining a longitudinal coordinate of the outer surface of        the cornea for at least six of the longitudinal A-scans; and    -   fitting a three-dimensional function to the determined        longitudinal coordinates.

19. The method of Example 17 or 18, further comprising determining thelocation of a corneal apex by calculating the location of an apex of thethree-dimensional function.

20. The method of Example 19, further comprising calculating a gazevector normal to the cornea at the corneal apex.

21. The method of any one of Examples 18 to 20, wherein thethree-dimensional function comprises a paraboloid.

22. The method of any one of Examples 18 to 20, wherein thethree-dimensional function comprises a symmetric function.

23. The method of any one of Examples 18 to 20, wherein thethree-dimensional function comprises a rotationally symmetric function.

24. A method of detecting an eye gaze direction, the method comprising:

-   -   performing an OCT scan of at least a portion of an iris and at        least a portion of a pupil of an eye;    -   determining a location of at least one pupillary border of the        eye with respect to a longitudinal meridian based on the OCT        scan; and    -   calculating an eye gaze direction based at least in part on the        location of the at least one pupillary border.

25. The method of Example 24, further comprising determining a lateraldistance between the pupillary border and a longitudinal meridian.

26. The method of Example 24 or 25, wherein the location of thepupillary border is determined in one dimension.

27. The method of Example 25 or 26, wherein the eye gaze direction iscalculated based on the lateral distance between the pupillary borderand the longitudinal meridian.

28. The method of any one of Examples 24 to 27, wherein the OCT scancomprises a first two-dimensional B-scan taken along a first lateraldirection.

29. The method of Example 28, wherein the OCT scan further comprises asecond two-dimensional B-scan taken along a second path different fromthe path of the first B-scan.

30. The method of Example 29, wherein the location of the pupillaryborder is determined in two dimensions.

31. The method of any one of Examples 24 to 30, wherein calculating aneye gaze direction comprises calculating an angle between a point ofgaze and a longitudinal axis.

32. The method of any one of Examples 28 to 30, further comprisingcalculating a pupillary midpoint location based on the firsttwo-dimensional B-scan and the second two-dimensional B-scan.

33. The method of Example 32, further comprising calculating a gazevector normal to the pupil at the pupillary midpoint.

34. A method of detecting an eye gaze direction, the method comprising:

-   -   performing a first OCT scan of at least a portion of an iris and        at least a portion of a pupil of an eye;    -   determining a first location of at least one pupillary border of        the eye based on the first OCT scan;    -   performing a second OCT scan of at least a portion of an iris        and at least a portion of a pupil of an eye;    -   determining a second location of at least one pupillary border        of the eye based on the second OCT scan; and    -   calculating a change in eye gaze direction based at least in        part on the difference in the first and second locations of the        at least one pupillary borders.

35. The method of Example 34, further comprising determining a lateraldistance between the first and second locations of the at least onepupillary borders.

36. The method of Example 35, wherein the change in eye gaze directionis calculated based on the lateral distance between the first locationand the second location.

37. The method of any of one of Examples 34 to 36, wherein the locationof the pupillary border is determined in one dimension.

38. The method of any one of Examples 34 to 37, wherein the OCT scancomprises a first two-dimensional B-scan taken along a first lateraldirection.

39. The method of Example 38, wherein the OCT scan further comprises asecond two-dimensional B-scan taken along a second lateral directiondifferent from the first lateral direction.

40. The method of Example 39, wherein the location of the pupillaryborder is determined in two dimensions.

41. A method of detecting an eye gaze direction, the method comprising:

-   -   performing at least two OCT scans of at least a portion of an        iris and at least a portion of a pupil of an eye;    -   determining a location of at least three pupillary border points        between said iris and said pupil of the eye;    -   determining a function based on the at least three pupillary        border points; and    -   calculating an eye gaze vector based on the function.

42. The method of Example 41, wherein a first OCT scan of the at leasttwo OCT scans detects at least one pupillary border point, and wherein asecond OCT scan of the at least two OCT scans detects at least twopupillary border points.

43. The method of Example 41 or 42, wherein determining a functioncomprises fitting a function to the at least three pupillary borderpoints.

44. The method of any one of Examples 41 to 43, wherein the function isa planar function.

45. The method of Example 44, wherein the planar function is a circle.

46. The method of Example 44 or 45, wherein the eye gaze vector isnormal to the planar function.

47. A method of detecting an eye gaze direction, the method comprising:

-   -   performing at least two OCT scans of at least a portion of an        iris and at least a portion of a pupil of an eye;    -   determining a location of at least four pupillary border points        between said pupil and said iris of the eye; and    -   calculating an eye gaze vector based on the four pupillary        border points.

48. The method of Example 45, wherein the four pupillary border pointsare obtained from two OCT B-scans through the pupillary border betweenthe pupil and the iris of the eye.

49. A method of detecting an eye gaze direction, the method comprising:

-   -   performing at least one OCT B-scan of at least a portion of an        iris and at least a portion of a pupil of an eye;    -   determining a location of at least one pupillary border point of        the eye based on the OCT B-scan; and    -   calculating an eye gaze direction based at least in part on the        location of the at least one pupillary border.

50. The method of Example 49, wherein the method comprises performing atleast two OCT B-scans, each OCT B-scan including at least a portion ofan iris and at least a portion of a pupil of an eye.

51. The method of Example 49 or 50, further comprising determining alocation of at least two pupillary border points of the eye.

52. The method of Example 51, further comprising determining a locationof at least three pupillary border points of the eye.

53. The method of any of Examples 46, 48, 51, or 52, further comprisingcalculating an eye gaze direction vector.

54. The method of any one of Examples 50 to 53, wherein calculating aneye gaze direction comprises calculating a vector along the line ofintersection between a plane orthogonal to a first OCT B-scan of the atleast two OCT B-scans and a plane orthogonal to a second OCT B-scan ofthe at least two OCT B-scans.

55. The method of Example 50, wherein calculating an eye gaze directioncomprises calculating a first vector normal to a first line between twopupillary border points along a first OCT B-scan of the at least two OCTB-scans, said first vector lying in the plane of the first OCT B-scanand intersecting said first line at the midpoint of said first line.

56. The method of Example 55, further comprising translating the firstvector laterally to a location where the translated first vector lieswithin a plane orthogonal to a second OCT B-scan of the at least two OCTB-scans at the midpoint of a line between two pupillary border pointsalong the second OCT B-scan.

57. The method of Example 56, further comprising calculating a secondvector normal to a second line between two pupillary border points alongthe second OCT B-scan of the at least two OCT B-scans, said secondvector lying in the plane of the second OCT B-scan and intersecting saidsecond line at the midpoint of said second line.

58. The method of Example 57, further comprising translating the secondvector laterally to a location where the translated second vector lieswithin a plane orthogonal to the first OCT B-scan at the midpoint of aline between two pupillary border points along the first OCT B-scan.

59. The method of Example 58, further comprising calculating a summedeye gaze direction vector by summing the translated first vector and thetranslated second vector using three-dimensional vector addition.

60. The method of any one of Examples 56 to 59, wherein the second OCTB-scan of the at least two OCT B-scans is orthogonal to the first OCTB-scan,

61. The method of Example 51, wherein calculating an eye gaze directioncomprises calculating an eye gaze direction vector in one lateraldimension, said vector intersecting the midpoint of a line between twopupillary border points.

62. The method of Example 61, wherein the eye gaze direction vector liesin the plane of the OCT B-scan.

What is claimed is:
 1. A method of detecting an eye gaze direction oreye position, the method comprising: performing at least two OCT Bscans, each OCT B-scan including at least a portion of an iris and atleast a portion of a pupil of an eye; determining a location of at leastthree pupillary border points between said iris and said pupil of theeye based on the OCT B-scan; determining a function based on the atleast three pupillary border points, wherein determining a functioncomprises fitting a function to the at least three pupillary borderpoints; and calculating an eye gaze vector based on the function.
 2. Themethod of claim 1, wherein a first OCT scan of the at least two OCTscans detects at least one pupillary border point, and wherein a secondOCT scan of the at least two OCT scans detects at least two pupillaryborder points.
 3. The method of claim 1, wherein the function is aplanar function.
 4. The method of claim 3, wherein the planar functionis a circle.
 5. The method of claim 3, wherein the eye gaze vector isnormal to the planar function.
 6. The method of claim 1, whereincalculating the eye gaze vector comprises calculating a vector along theline of intersection between a plane orthogonal to a first OCT B-scan ofthe at least two OCT B-scans and a plane orthogonal to a second OCTB-scan of the at least two OCT B-scans.
 7. The method of claim 1,wherein calculating the eye gaze vector comprises calculating a firstvector normal to a first line between two pupillary border points alonga first OCT B-scan of the at least two OCT B-scans, said first vectorlying in the plane of the first OCT B-scan and intersecting said firstline at the midpoint of said first line.
 8. The method of claim 7,further comprising calculating a second vector normal to a second linebetween two pupillary border points along the second OCT B-scan of theat least two OCT B-scans, said second vector lying in the plane of thesecond OCT B-scan and intersecting said second line at the midpoint ofsaid second line.
 9. The method of claim 8, further comprisingcalculating a summed eye gaze direction vector by summing the translatedfirst vector and the translated second vector using three-dimensionalvector addition.
 10. A method of detecting an eye gaze direction or eyeposition, the method comprising: performing at least two OCT B-scans,each OCT B-scan including at least a portion of an iris and at least aportion of a pupil of an eye; determining a location of at least threepupillary border points between said iris and said pupil of the eyebased on the OCT B-scan; determining a function based on the at leastthree pupillary border points, wherein the function is a planarfunction; and calculating an eye gaze vector based on the function. 11.The method of claim 10, wherein the planar function is a circle.
 12. Themethod of claim 10, wherein the eye gaze vector is normal to the planarfunction.
 13. The method of claim 10, wherein calculating the eye gazevector comprises calculating a vector along the line of intersectionbetween a plane orthogonal to a first OCT B-scan of the at least two OCTB-scans and a plane orthogonal to a second OCT B-scan of the at leasttwo OCT B-scans.
 14. The method of claim 10, wherein calculating the eyegaze vector comprises calculating a first vector normal to a first linebetween two pupillary border points along a first OCT B-scan of the atleast two OCT B-scans, said first vector lying in the plane of the firstOCT B-scan and intersecting said first line at the midpoint of saidfirst line.
 15. The method of claim 14, further comprising calculating asecond vector normal to a second line between two pupillary borderpoints along the second OCT B-scan of the at least two OCT B-scans, saidsecond vector lying in the plane of the second OCT B-scan andintersecting said second line at the midpoint of said second line. 16.The method of claim 15, further comprising calculating a summed eye gazedirection vector by summing the translated first vector and thetranslated second vector using three-dimensional vector addition. 17.The method of claim 10, wherein a first OCT scan of the at least two OCTscans detects at least one pupillary border point, and wherein a secondOCT scan of the at least two OCT scans detects at least two pupillaryborder points.